I Traffic
Accadentr
chapter 5
TrafficAccidents
Traffic accidentson the highway are an unfortunate and not completely economiccost of highwaytransportation. The cost of accidents is unavoidable includedin the cost of highway travel in the same sensethat motor vehicle runniig cost is included. Highway accidents bear a relationship the mileage to is of motor vehicles, thereforethe cost of motor vehicleaccidents properly so considered a road usercost in the marketclass. The overallcostof accidents as involves costof motor vehicle the and medical commodities. traveltime.nontravel pain, and the nonpriceable time, professional and other personalservices, anguish, suffering, and sentimentalities involved. Unfortunately, the purpose for studies highwayimprovement, costof trafficaccidents not the has of economy of yet been reduced a suitable to basisand the accident rateshavenot beenclosely enoughassociated with highwaydesignand traffic operations. The following setsforth the main considerations an effort to focusthoughtupon in discussion and highway design. the relationof highwayaccidents economy,economlcs, to rates presented guides usein economy studies. Someaccident are as to
Accident is thar cl unintended injury. dcrQ Motor vehicle aail that results in dcath, I motor vehicle is not n{ and a motor vehiclc. S Motor vehiclc trd rry or placc, any pat{ rliqrlar trafFrc. I
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REPORTING
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CLASSIFYING
ACCIDENTS
come from official reportsmade Certain facts on motor vehicleaccidents persons involved andby within a few hoursor a fewdaysofthe accidents those by usuallyhas to be traffic officers. The correct and completecost of accidents and investigations.Accidentfacts,otherthan obtainedby follow-upinterviews for in though not alwaysin the detaildesired cost, are extensive the literature, are economystudies,but accurateand completecostsof accidents practically systemis helpful in of nonexistent. A discussion the reportingand classifying and the traffic accidentratesto usein engineerdeterminingthe cost of accidents ing economy studies. DEFINING ACCIDENTS of Thereare several definitions the word "accident"andstill wideruses the of word when restricted highwaytravel. The National SafetyCouncil [5-36, to p. 971 gives following the definitions: 36()
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Accident is that occurrence in a sequence of events which usually produces unintended injury, death. ur property damage. Motor vehicle accident is any accident involving a motor vehicle in motion that results in death, injury, or property damage. However, motion of the motor vehicle is not required in a collision between a railroad train or a streetcar and a motor vehicle. Motor vehicle traffic accident is a motor vehicle accident which occurs on a w a y o r p l a c e . a n y p a r t o f w h i c h i s o p e n t o t h e u s e o f t h e p u b l i c f o r p u r p o s e so f v e h i c u l a rt r a f f i c .
These three definitions narrow the meaning down to a practical basisfor t is to !Sgtrrruy economicstudies. Further classification desirable afford a proper the tut" for understanding literature,particularly0ertainwritings on numbersof I of I rcidents andcosts accidents. There is a difference between motor vehicleaccidentand a highwaytraffic a I Collisions parkinglots and at one'sgarage on door are motorvehicle !rcident. but not traffic accidents because site of the accident not on a the is leccidents, publictrafficway. I A traffic accident involvesa vehicle on a trafficway and in rnotion(a vehicle I involvesa vehicleon a *iking a fixed object or anothervehicle);a traffic incident | but without the vehiclebeing in motion (a falling ladderstrikinga !rrafficway, asvandalism, tl5-251resultfrom suchevents fnarkeO vehicle). Traffic incidents riots. fires,explosions, storms, snowslides,. collisions and from nonmotorvehicles ! equipment fallingobjects. and ! ruchasconstruction A traffic accidentinvolvement one vehiclein an accid.ent. An accidentin is t r'hich two vehicles of collide consists two involvements. For somepurposes, I eccident cost information reported on an involvement,or singie vehicleas the ! baseunit of enumeration,is best, but collectingaccidentcost by involvements is I u expensive expedientbecause costsmust come from the owner or driver of the I by is I cachvehicle. The numberof traffic accidents the otherunit of enumeration r'hich accidents reported. Accidents suchinvolveoneor morevehicles, so are as I traffic accident is composedof one or more involvements. For economy le is records.and other fenalyses the per accidentaccounting more usefulbecause on rccident informationare most often avarlable an accidentbasisratherthan f basis. an involvement I on
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to require certain motor vehicleaccidents be reported Laws and ordinances I governmental form. Usuallyall accidents agency a prescribed on ro a designated I property I that result in personalinjury and death are requiredto be reported"and when the damageis abovea minimumsum. are damageonly accidents reported J of as $50, $ 100.or $200. Theseofficialreportsare the source mostofthe J ruch perhaps only but basis, statistics highway on accidents, on an accident summarized J 50 percent of all traffic accidentsare reported. Although theseofficial reports | I
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arereasonablycompleteinthedetailsoftheaccident,theydonotreportthe The medical other than an estimateof property damage' costs of the accidents months' and evenyearsfollowing and other costs must be collected in the weeks' theaccidentandfromthosepersonsortheirsurvivorswhosufferedthecosts. neithercompletenor accurate' on But suchstatistics costare-often ThroughtheeffortsoftheNationalSafetyCouncil,statedepartmentsof motor companies'and other agencies' safety and of motor vehicles,insurance country' more uniform over the vehicle accidentofficial reporting is becoming b u t i s s t i l l f a r f r o m i d e a l . A c c i d e n t s t a t i s t i c s , t h e r e f o r e , c a n b e s be classified a n d ummarized basis' Also' they can analyzedon a local, "oonty, state,or national driver' the vehicle'the highway'the by many key lactors p",,uining to the vehicle time of day,and day of the week' weather, Inspiteofthedetailinwhichmotorvehicleaccidentsarereported,thecritical studentoranalystofaccidentsusuallyfindsthereportsorsummarieslacking, Someofthemainitemsimportanttothehighwaydesignerandeconomicanalyst m o s t o f t e n n o t r e p o r t e d i n s u f f i c i e n t d e t a i l a r e t h e e x a c t l o c a t i o n oroadway' i c fthetraff ofhighway design'exactspot on the to accidentwith respect the features a n d t h e t r a f f i c c o n d i t i o n s a t t h e t i m e o f t h e a c c i d e n t . W i t h r e s p e c t t olike' d s i d e roa crests' accesspoints' and the objects, curbs, shoulders,ditches' sumps' 5orl0feetofdistancemaybeimportanttotheanalystoftrafficaccidents' Becausethelawu,uuttydoesnotrequireminoraccidents(baseduponmini. becausemany lawfully reportable mum property damage)to be reported' and picture of motor vehicle accidentsis not accidentsare not ."pott"d, the total k n o w n . T h e u n r e p o r t e d t r a f f i c a c c i d e n t s a r e m o r e n u m e r o u s t h a n t h o s Seep o r t e d ' ere tl5-25' p' XX and l5-4' p' 2031' and their total cost i, iigttty significant alsopage400 and Table l5-9A' reports include all accidents More often than not, motor vehicle accident i n v o l v i n g a m o t o r v e h i c l e r e g a r d l e s s o f w h e t h e r t h e a c c i d e n t o caccident f f t h e curredo studiesit is only the traffic highway or in moving traffic' For economy thatiswantedbecausethetrafficaccidentisaffectedbyhighwaydesignand t r a f f i c o p e r a t i o n s . A c c i d e n t s o n p a r k i n g l o t s , i n p a r k i n g b u i l d i n g s ,they r i v a t e onp to highway design except as land, and in repair garagesare unrelated Illinois accident cost study tl5-251 affect accessto tne iubli'c highway. The seParatesthemotorvehicleaccidentsintotrafficandnontrafficaccidentsand traffic and nontrafficincidents' CLASSIFYING ACCIDENTS summarizedin many ways to Motor vehicle accidentsare classifiedand Ref' l5-36' Accident Facts'published satisfythe many usesoiitre statlstics' See bytheNationalSaietyCouncil,Chicago.Butunfortunatelythemanyreported classificationsoimotorvehicleaccidentslackmuchwhenappliedtotheanalysis design features' the traffic of highway engineeringeconomy' The highway ratesare usuallynot reported' volumes,and the exposure
One of the most useful -vcrity into (l) fatal injury Foperty damage only accidentr. hd injury and nonfatal injurY tc also reported by numbersof tr also reported by this i lnown, the total traffic accidctrt cation Another useful classifi (3) Dtor vehicles, other collisiorl { In turn, each of thesefour gro( rehicles at the moment of accidd -tersection, one car parked, hittirl thatl Still anotherclassification bthe action of the driver of thc vdl Speedtoo fast Drove left of center Failed to yield right-of-way stop sign Passed
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; These eight actions of the driq is the reason these actions { but not reported, arc { lighti{ putting on sunglasses, problc{ a personalor business The reported summariesof ml do not generally classify th{ :, by traffic characteristica lions are given for certain { by type of vehicle may bc{ than for nonfatal injury a with but little detail. I 'I To get traffic accident rate ql traflic charactenstrca r- I and traffic characteristicrI { to detailed analysesof thc q nl interviews, and pcrsoo{ and other organizati! ;rblications as given in th{ :o such major reports as { fo{ full information n6edodfor{ (l) thc { Fmary factors: of thc accidents,(2) it u{ making the analytical d
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one of the most useful classifications the simple three-waygrouping of is severity into (l) fatal injury accidents,(2) nonfatal injury accidents,and (3) property damage only accidents. Property damagesusually result, also, from fatal injury and nonfatalinjury accidents. The fatal and nonfatalinjury accidents are also reportedby numbersof.persons involved. when the costsof accidents are also reported by this classification and the rate, or frequency,of accident is known, the total traffic accidentcost is easilycalculated that classification. for Another useful classification (l) pedestrian is (2) accidents, collisionbetween motor vehicles, other collision,and (4) noncollision. (3) In turn, each of thesefour groupsis divided into the action of the vehicleor vehiclesat the moment of accident, such as going straight, turning, entering intersection, one car parked, hitting fixed object, overturning,and many others. Still anotherclassification that bearsupon economystudies that pertaining is to the actionofthe driver ofthe vehicle. In this groupingare found suchitemsas: Speedtoo fast Drove left of center Failedto yield right-of-way Passed stopsign Improper overtaking Disregarded signal Made improperturn Followedtoo closely
Theseeight actionsof the driv,ercorrespond violationsof traffic laws and to that is the reason these actions are on the oflicial reports. perhapsof equal importance,but not reported, are other actions of the driver, such as readinga map, putting on sunglasses, lighting a cigarette,listening to the radio, thinking ebout a personal business problem,etc, or The reportedsummaries motor vehicleaccidents of suchas found in Accident Facts,do not generallyclassifythe accidentsby highwaydesigntype, by traffic volume, by traffic characteristics, by highway system. Rural and urban or rparations are given for certain types of accidents,and some overall accident totals by type of vehicle may be given. More detail is given for fatal injury rccidents than for nonfatalinjury accidents; property damageonly accidents are pnblished with but little detail. These general statisticsare national or state totals. To get traffic accidentratesand costsas relatedto highwaydesign, highway tystem, and traffic characteristics needed economystudies, as in recourse mustbe teken to detailed analyses the original accidentreports,accidentby accident, of pcrsonal interviews, and personal examination of accident sites. Highway &partments and other organizations have reportedthe resultsof suchanalyses in och publications as given in the list of references the end of this chapter. at Even such major reports as Refs. 15-25,15-42,and l5-50 however.are short of the full information neededfor economystudies. This shortageresultsfrom lhree primary factors: (l) the information was not available in the official rcports of the accidents, it wasjudged too costly to get the information,and (2) (3) those making the analytical studieswere not awareof the needson accident
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important studies' This latter factor is an statisticsfor applicationto economy sufficiently about the person has ever thought one, because perhapsno one for specific fot Inotot vehicle accidentstudies *t;;;;i"'i processto come tp The importantinformation ot to highwaydesign' applicationto ".onorny 'tJi"' and say by iatal injury, nonfatalinjury' "ori of accidenls. not usuallygiven is ,n" and to the designtype of to the traffic volume property damage""1y, i;;;;ion acto intersection of missinginformation relates highway. Another t*urnpi" c i d e n t s f o r w h i c h t t u f t i " n o * ' n u m b e r o f l a n e s a n d t h e i r w i d tand n d t h e t r a f f i c h ' a Associates factors' Further' Wilbur Smith control devicesu" irnio'iunt cost only on an involvementbasis' ll5-42lreport the traffic accident and accidents of reports and summaries traffic In general,unury'"I "i "ntt't use in educationof therefrom' have general the published statisticsresulting and in overallpublicity Uu"tgtounJ' in licensingof drivers' drivers,as legislative highwaydesign' traffic engineering, and th"ir cori. They also serve on accidents of accidents' in those areas of concentration and law enforcement,especially of accidents' eitherby highwaylocaiionor cause ACCIDENTS AND ECONOMY
a view toward reducing tho{ lnaffic has grown heavier and i lumber and in total cost. Col rithin highway departments to{ cffort into accident reducing adl rnd traffic operation. These d
and in humandistress' For economy are Highway accidents costlyin dollars may be transportation' traffic accidents and economic studies of highway of and consumption of consumption commodities to in considered respect their they have not on highway accidents-' 'yet time. Despite the extensiveliterature of to satisfythe objectives the Lasis an adequ-ate been reported and analyzedon discussion in highway improvements' Some analysisfor choice of aiternatives and their nature of accidents the understanding from this viewpoint *'t' nap in transportation' in economy highway role in attaining PUBLIC ATTITUDE ACCIDENTS, ECONOMY,AND avoided' unwanted' unsoughtcoststo be The costs of traffic accidentsare alternatives Economy studiesof highway at but not necessarily any expense' of the nondollar marketprice basis' Because be must necessarily plac"d on'a physicalsufferings and pain, misery' and personal mental priceablesubsequent warranted expenditureof highway funds is an from personal injury accidents' c o n s i d e r a b l y a ' b o v e t h a t l e v e l j u s t s u f f i c i e n t t o p r o d u c e a b a l coste b e t w e e n o u t g o a n c of traffic accountablereduction in the for accident reduction una itr" a c c i d e n t s . M a n a g e m e n f a c t i n g w i t h i n p u b l i c p o linvest aboveitheslevel e p u b l i c , i s i c y a n d d e s r e o f t h of fto* *uth money to responsiblefor the decision ol of economyasa first needsto know the facts dollar returns. Sut t"nug"'nent of basis makingits iinal decision' operations on highway design and traffic There always t'ut Ut"n "tphasis
lrallic accidents. The probiem facing the Smstruct a safe highway for ly, t'dy, but they drive unsafely. unsafely{ol ling actions.drive when sl{ rm, drive unsafe vehicleg { ditions oi high risk, and gcol ing real valuesin return fortbl The American driving publicr mt want to pay the financiJi safety in traffic. Thclt iated with unsafe driving { e. This same feeling is crf irnpressionthat while it is I as a natlon we seemuq of accidents." How d and how much will bc d{ 3, es cxpressed Hall llt{ by me in my belief thst q safety on our streetsand,
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d highway accidents wc I end economically bauri red by not having tnrl e public policy and tward a definitc -cilcnts arc a c'omplcl end cngincering. notinc, high*zy r nuc-h traflic safcty rd ar much as thc
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with a view toward reducing the number and severity of traffic accidents. As traffic has grown heavier and more concentrated, accidents have increased in number and in total cost. concurrentry, there has been a growing practice within highway departments to prace ,no.e "mpharis on anJ relativery more effort into accident reducing andaccident prevention elementsof highwaydesign
illriJ::h:peration.
rhese effbrts pu.ull"l generat the prtri" lrimor against
ll5-lgj, when in rg62he said: ,.Alr of thesethings confirm me in my belief that the one greatest reasonwe aren,t movingfaster safetyon our srreets and highwaysis that as a people *" Oon,thavethe ::1i: This attitudeof the pubtic suggests the need for research determine to the level of highway accidents*" *-, to rive with. what is a good balance rccially and economica'ybetween havingtraffic accidents and the sacrifice td be suffered by not having traffic accid-ents?perhaps if this question were answereda public poricy and program would folrow whereby a more positive movement toward a definite. and reachabre goal could be pubticry agreed upon. Traffic accidents a comprex are probremof slciety involvingpolitics, economics, sociology, and engineering. In the meantine, highwayofficialsmust continue their effortsto build into highwaysas much traffic safetyas their technicar knowledge and earnest endeavor can suppryand as much as the pubric wilr supplymoneyfor. E"ono-y studies furnish goodguidefor carrying a out these,*oli.rn, of policy. L'SEOF TRAFFICACCIDENT DATA IN ECONOMY STUDIES Considering that traffic accidents ."surtin oneelement the cost of of highway
driving how ''r be u."unun,lli*";;::,i"1:1'' and 'u"r' done lT"t:ilnTl: much as expressed Hail by
it is generaily considered thereu," ,.,o ,uny that :::,ili:::::'":1,:"Tnt'. '|t"T theprice required a further tbr reduction accidents.lt Tfflffi:ooPaY or
The problem facing the highway designersand the traffic engineers is to construct a safe highway for unsafe drivers. Most drivers know how to drive safely,but they drive unsafery-too fast for conditions, take chances turning and in passing actions'drive when sreepy, drive with too much arcoholin their blood stream, drive unsafe vehicles, overtake and pass and changc lanes under conditions high risk, and generaily of contributeto accidentfrequency without getting realvalues returnfor theirunnecessary in risks. The Americandrivingpublicdoes not want safehighways-that the peopre is, do not want to pay the financial cost and to suffer the restrictions necessary to produce safety in traffic. They would rather pay more for the accidentcosts associated with unsafe driving than to sacrifice their freedom ,o i.iu" as they please. This samefeelingis expressed HafrtaA U5_l7l: ..One Uf quicklygains
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transportation,theeconomyaspectsoitrafficaccidentsshouldbeinvestigated cost and motor vehiclerunning in the same detail as are the factors of highway economyonly' that is' for the moment cost. For the purposeof the analysisof notconsideringthedesiretoreducehumanmisery'accidentsmaybetreatedmuch inthesamewayasarethehighwaycoststreatedinrelationtomotorvehicle runningcosts. to improvementof traffic Three generalapplicationsof economy analyses safetymaybestated:(l)spotimprovementswiththesingleintentionofreducing theaccidentrateoraccidentseverityatthatspotonthehighway'(2)project improvementorageneralimprovement,reconstruction,orconstructionofahigh(3) transportationsystemplanning' *uy .out" or sizable ,"g."nt thereof, and (often urban) and perhapsall wherein all the highway facilities within an area thereinare considered' modesof transportation Forthesethreeapp|icationstheappropriateformofaccidentdatamayvary somewhat.Ingenera|,whatisneededisthecostofaccidentsexpressedincost per million(or 100million) per p"r per accident, inuoluernent' mile of highway'or accident rate for each vehicle-miles. The second sei of information is the The accidentrate may be of the improvement alternativesbeing considered' expressedasaccidentsorinvolvementspermillion(orl00million)vehicleas an example)'per miles of travel, per million vehicles(for an intersection highwaymile,orasapercentagereductionfromaknownbase'suchasforthe up a source for both existing facility. The literature is gradually building costofaccidentsandaccidentrates,buttherearestillwideanddeepgapsof of areas wantedinformation. Spotimprovementstoreduceaccidentsarecommonandsimpleinanalysis. Percentagereductioninaccidentsandseverityaregoodmeasuresoftheaccident reducingefficiencyoftheimprovementsconsidered.Typicalspotimprovements lighting, bridge widening,curve selective are intersectiontraffic control devices, of coefficient frictionof and sight distances, increasing lengthening lengthening, the road surface. betweensuch Route improvementprojects call for accidentcomparison factorsashorizontal.u,u",'verticalgrades'numberoftrafficlanes'medians' rates accident control' In thesetypesof improvements' of and degrees access are most tralfic volumes of related to total vehicle-miles travel for specificdaily may require however,such as for curvesand grades, often used. Subanalyses, rate basedupon the rate more specificinformation or a relativefactor of accident for leveltangents. Forareasystemplanningstudies'overalltrafficaccidentcostsbasedupon for costs may be expressed oi annual vehicle-miles tr"u"i are desirable. These generaltypesofhighwaysorstreetsandtheirgenerallocation.Typicalneeds areas, and business residential serving on are for annualaccidentcosts local streets locations' and freewaysfor rural' suburban' and urban arterials, expressways'
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The total net cost of anYd to determine than most Perso phase of the effort to determil What offsetting benefits are t accidentby peoPleassociated other similar questions mq difficulty of finding the dollar { is made on what costs and tii immediately after the accidcdi to of costs. It is necessary d the people involved in the acl order to get the correct total'i fatal personalinjurY accidend col accident. But in highwaY and should be calculated ud studiesso far made on high{ and put them together in aforl improvements. Two PrimarY rmdies. First, the analYstsI Ggonomystudies, and, sccon{ eblc. ACCIDENT CTJISSIFYING Thc cost clements Thcsc clcmcots Lrclvd. sctcmc scrvcs thc rlch
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COST OF TRAFFIC
The total net cost of any one singlehighwaytraffic accidentis more difficult to determinethan most personsbelieve. The first difficulty is in the planning phaseof the effort to determinethe costs. what cost items are to be included? what offsetting benefits uri to b" included? How is the time devotedto the accidentby people associated therewithto be accountedfor and priced? Many other similar questions must be answered. Second, there is the practical difficulty of finding the dollar costsand the clock time consumed oncea decision is made on what costs and time are wanted. The official accidentreportsfiled immediatelyafter the accidentcan contain only preliminaryand partial estimates of costs. It is necessary contactappropriaterecords,public and private,and to the people involved in the accidentor associated therewithafter the accidentin order to get the correct total cost. For someaccidents, especially seriousnonfatal personalinjury accidents, costsmay be incurred for l,2,or 3 yearsafter the accident. But in highwayeconomystudies accidentcostsare an important factor and should be calculated using the best estimatesavailable. Despite all the studiesso far made on highwaytraffic accidents one hasyet collected data no the and put them togetherin a form suitable economystudies proposed for of highway improvements. Two primary factors contributeto this shortcoming accident in studies. First, the analystshave not had in mind the needsof informationfor economy studies,and, second,the necessary information was not readily available. CLASSI FYING A CCIDENT COST ELEM ENTS The cost elements within the total costsof traffic accidents manyand are are involved. Theseelements may be classified several by schemes, depending upon which schemeservesthe purposesto greater advantage. There are direct and indirect costs, on-site and off-site costs, immediate and future costs, cash costsand noncashcosts,cost ofgoods and cost ofpersonalservices, coststo those involved in the accidentand the coststo others,priceablecostsand unpriceable costs,and tangibleand intangiblecosts. No one classifying systemwill serveall purposes equaladvantage. to In the ordinary reporting systemthe on-site costs are limited to propeny damageto the vehicle and its contents, and perhapsto the highwayand roadside property, ambulances,and a few other items that can be observedat the time of the accident. The off-site costsprimarily are those associated with treatmentof injuries, legal and court costs, and time factors. There is really no positive schemeto separatedirect from indirect costs,tangible from intangible costs,and likewisefor the other schemes. The important thing to know, however,is what cost elementsare included in any report of traffic accidentcosts. only then do the statedtraffic accident costshavereal meanins.
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As with most transactions involvingthe dollar, a disbursement one person by resultsin an income for another;the income can be the equivalentof saleswhen commodities services purchased, or are and largely net incomewhen direct labor is purchased. To the disburser,however,the full amount disbursed a cost to is him. Specialinvestigations traffic accidentcostshave usuallyconcentrated of on the cost items of property damage,medical, legal, and wageslost for two main (l) reasons: The costsborneby the individuals directlyinvolvedin accidents are more readily obtainedthan the other costs,and (2) thesecostsusuallyamountto a high percentage the total. Nevertheless, of someattentionshouldbe givento the total of all economiccosts,at leastuntil somegeneralratio of the costof these indirectand gener_al itemsto the direct and specificcostcan be established. The following nine groupings(A to I) of traffic accident cost items are an attempt to bring to light and into sharper focus the many and varied cost elementsregardless their magnitude. The classificationschemeservesthe of purpose (l) emphasizing costsfor consumable (2) of the goods, personal services, (3) time utilization by all individuals,and (4) privatecostsseparated from government costs. Each of the nine groupingsis discussed the sectionsto follow. in ELEMENTSOF COST AND BENEFITS ASSOCIATEDWITH HIGHWAY TRAFFIC ACCIDENTS A. Goodsand otherproperty consumed l. Parts and labor for restoration of damagedproperty-motor vehicles, highways, buildings, otheritems and propertydamaged 2. Clothing and personal 3. Cargo in freightvehicle 4. Mealsawayfrom home 5. Medicines, appliances, medicalsupplies includedin physicians' not fees or hospitalcharges gifts,andspecial 6. Flowers, candy, purchases because only ofthe accident 7. Domestic animals andwildlifekilledon the highway B. Transportationand communications l. Ambulance andotherrescue vehicles 2. Tow truck 3. Taxi 4. Hire of other vehiclesby all concerned, includingtransportationfor the disabled 5. Publictransportation-from and near-bythoseinvolved far 6. Extra travel by motor vehiclesfor trips pertainingto accidentby all persons all purposes, for includingpolicevehicles 7. Commercial rentals and taxicab fares lost because damaseto rental of and taxicabvehicles 8. Lost useof damaged commercial vehicles
9. Motor vehicleoPeratit4l el, changes ing, and sPeed 10. Extra useof mail, telePh{ li television, I t. NewsPaPer, C. Personal i"rvices rendered'I in rentsincluded the wagesar anddentists' l. Physicians' 2. Lawyers'fees 3. Nursingfeesother than q 4. Hospital servicerentitc, therein and finesasli 5. Court costs andcosts i lees 6. Witness 7. Additional hire at homo'i 8. Additionalhire at workfl 9. On siteand otherassiste bY D. Time consumed all Persor l. Lost work time of thosc accident-allPurposes 2. Lost work time of thosct accident 3. Nonwork time of relatiq r{ the accident-accident of replacement damaged I . 4. Probablefuture work tii 5. DelaY time and other q
accident insurl including Unclassified, E. awardedabovl l. Damages 2. Presentworth differend death exPected 3. Financing exPense-loa to paYaccidentcosts i a 4. Illness ndaccidentsto 5. Motor vehicleliabilitYI insuredlessclaimsPaid , Workmen's comPensat 6. to assignable highwaY { ao{ miserY, Anguish,anxietY, F. grief,distress' I . MiserY, { fatigue'rl of sleeP' 2. Loss bnl 3. Mental and PhYsical anddutiesfor 4. Pleasures
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9. Motor vehicle operating expenseto traffic lor delays, extra distance routing, and speedchangesat time ofaccident 10. Extra use of mail, telephone,telegraph' and other communications I l. Newspaper, television, magazine, and other coverage of accidents Personal iervices rendered, including the overheads, goods, supplies and rents included in the wagesandfees ofthose rendering the services l. Physicians'and dentists'fees,including total expenses 2. Lawyers'fees 3. Nursing fees other than received through hospital service 4. Hospital services-entire staff-and goods and other services included 5. 6. 7. therein to Court costsand fines assessed accident involved persons Witness feesand cQsts Additional hire at horne'domestic help Additional hire at work place to replaceabsentees On site and other assistancefrorn bystanders and passersby
8. 9. D . Time consumed by all persons affected l. Lost work time of those persons-injuredones and others-involved in the accident-all purposes 2. Lost work time of those concerned or affiliated with persons involved in accident devoted to any aspectof 3. Nonwork time of relatives, friends, associates reporting, court witnesses,consultation, repair or the accident-accident replacementof damaged property, telephoning,etc. 4. Probable future work time of deceasedand permanently injured persons 5. Delay time and other travel time of motor vehicles as a result of the accident Unclassified,including insurance l. Damages awarded above the costs otherwise accounted for 2. Present worth difference in funeral cost now and the future time of expected death 3. Financing expense-loansand loss of returns on investment withdrawn to pay accident costs 4. Illnessand accidentsto others brought on becauseofthe caseaccident 5. Motor vehicle liability insurance overhead cost-premiums paid by the insured lessclaims paid 6. Workmen's compensation insurance programs-prorata share of net cost F. assignableto highway traffic accidents Anguish, anxiety, misery, and suffering l. Misery, grief, distress, and suffering by all concerned 2. Loss of sleep, fatigue, and inconvenience to all concerned 3. Mental and physical breakdowns 4. Pleasuresand duties forgone
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avoided and normal expenses received G . Benefits I . Future living costof the deceased directly with motor 2. Insuranceclaims paid other than those associated employcompensation, vehicle liability coverage. Included would be ment,medical,and health discussed) court awards(previously 3. Damageand coiapensation to work and to social of 4. Savingin motor vehicleusebecause not traveling functions and recreational or transportation noneat all while car is beingrepaired 5. Useof cheaper ofbeing because 6. Food savedat home and at work and other expense confinedto hospital activities 7. Curtailedsocialand recreational 8. Many other smallitems and operations service H . Governmental for I . Court costsnot compensated by finesand fees procedures 2. Criminal and other prosecution and and expense-overhead operations 3. Police and highwaypatrol salaries public, and some (some private, some 4. Ambulance and rescueservices volunteerorganizations) 5. Collecting, reporting, filing, analyzing, investigating,and publishing relatedto traffic accidents reportsand statistics insurance and compulsory 6. Administrativecostsof financialresponsibility laws 7. Future income taxes not received on probable earnings not earned of because injury or death for of 8. Net of incometaxesnot paid because deductions medicalexpense and losses of 9. Inheritancetaxesnot paid because lesswealth at death-nowor laterreducedincome,or future incomenot resultingfrom accidentexpenses, earned of Note.'Items 7, 8, and 9 probably do not result in a net decrease ratesas is will raisetheir tax (l) tax income,because the governments to necessary raise the amount of their budgets,or (2) the incomesof others who make a financial gain from the accidentcost to the others, may pay greatertotal sumsof incometax than they would havepaid had I. not haPpened. the accident and their severity the Activitiesto reduce numberof accidents work for specific l. Highway construction of facilities and maintenance purposeof accidentpreventionincludingspot improvements and surveillance studies 2. Traffic engineering 3. Traffic officer operations 4. Educationand training programsfor drivers medicalservices 5. Emergency
a"
6 . CommunitY safetYP 7 . Committees, boards' 8 . Items on the motor Y of accident severity signalsYstc cylinders, 9 . Research and develoPl and treatment Goods and Other Propcnb d
l
Motor vehicle accidents o{ commoditiesin the samesen$ q fuel. rubber, and mechanicalP( important in magnitude. Mceb:l ofthct{ percentage no significant main grouPs'd Of the three I In fact, but incorrectlY ctly. lormal accident rePorts. Thd lc included. TheY can be ot{ hllowing the date of accidenl ; tc property consistsof the ud I rd indirect labor and serviccs' pe items are exaPtlY thc re{ of cs, and normal vehicle mait4 lhc samemannerin economY{ The off-site cost of comm{ I of the total off-site coet I rly just that associatcdwi{ es of accident costs rcgu4 all rc efforts to assemble o{ way all costscan be cibuirl Tnsportetion end
A traffrc accident, of travel and vehicles at thc ofthc and associates Other rodcs. damagedvehiclcsfc motor vehicle with by the rErouting ovcr
Traffic
Accidents
371
6. Community safetyprograms 7. Committees,boards,councils,and group activitiespertainingto safety 8. ltems on the motor vehicledesigned accidentpreventionor reduction lbr of accidentseverity-seat belts,collapsiblesteeringcolumns,dual brake paddedintetiors,etc. cylinders, signalsystems, 9. Researchand developmentcosts on traffic accidents,their prevention and treatment A Goodsand Other PropertiesConsumed-Group Motor vehicle accidents on the highways, roads, and streets consume of that motor vehiclesconsumethe commodities commoditiesin the samesense groups of items are fuel, rubber, and mechanicalparts. Only the first three important in magnitude. Meals away from home,gifts, and animalskilled areof percentage no significant ofthe total. Of the three main groups, the damageto motor vehiclesis by far the more costly. In fact, but incorrectly so, the other items are often not reportedwith normal accident reports. Thesenonvehicleitems are real, however,and should be included. They can be obtained only by careful investigationover time, or following the date of accident. The cost of repairingthe damages replacing (2)direct the property consistsof the usual three factors-(l) parts and supplies, and indirect labor and services, and (3) overhead expense suppliers. These of three items are exactlyof the samecharacteras are includedin the price of fuel, tiresoand normal vehicle maintenance. Therefore,they may be treatedexactly in the samemanner economy in studies. The off-site cost of commoditiesis usually never reported as such; in fact, much of the total off-site cost is never reported. The reported off-site cost is with medical attention to the injured. Full-scale usuallyjust that associated studies of accidentcosts require interviewswith individuals affectedand other sincere effortsto assemble costs, all accident accident. This procedure the by is only way all costs canbe obtained l 5-25,I 5-42,I 5-50]. I Transportation B and Communications-Group A traffic accident, particularly a personal injury type, brings into play a complex of travel and communication activity. In addition to the travel of emergency vehicles the time of the accident, at thereis local travel by relatives, friends,and associates the injured. Even intercitytravel takesplaceby one or of of more modes. Other transportationexpense occursbecause rental of vehicles vehicles both personal commercial for and use. to replace damaged ': not yet evaluatedis the cost to traffic which is One motor vehicle expense speed interfered with by the accident. This cost is composed idling motors, of changes,rerouting over longer distancesto destinations,and often secondary minoraccidents.
372
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Accidents
Traffic
Accidents
are The last two items of use of mails, telephone,and newscoverage quite minor in magnitude. Utah [15-50],and In accidentcost studies,such as those in Illinois Ll5-251, procedure wherethe home interviewand questionnaire washington, D.C. t15-421, was used, ambulancecost and loss of use of the casevehicleswere generally covered. collected. Other itemsof the l2 listedwerenot specifically C Rendered-Group PersonalServices run to high cost in fatal injury and nonfatalinjury Medical and legal services accidents. These items constitute the bulk of the cost in the personalservice group. not at Additional hire to replacethe services home or on thejob are generally of significant magnitude. The items in this group are the off-site variety that can be obtained only by detailed follow-up over time through interviewsand questionnaires. fees are It is assumedthat these professionalservicesand the associated is and that to reducethe cost to the road userfor theseservices a scarceresources could not services usedon traffic accidents desirableeconomy. The professional is be devotedto other outlets. This reasoning the sameas appliedto the saving in the direct runningcostof motor vehicles. by Time Consumed All PersonsAffected-Group D by of The hours devoted to all aspects traffic accidents personsnot directly amount to a surprisingly large total. The personsso compensatedtherefor and involved include the accidentvictims and their relatives,friends,associates, The time is devotedto telephoning, random personsaffectedsolely by chance. visiting the home and hospital involved, courtrooms,trips for medical service, and work relatedtrips. In addition, there is the time taken from work by these personsand the work time lost by the injured, for which someof thesepersons suffer somelossof wage income. Theseclock times are most difficult to collect and in most cost studiessuch attempts have been restrictedto getting only lost work time of the injured. report time taken Wages Lost. Most studiesof the cost of traffic accidents wage or salary rate of the from gainful employmentas a cost computed at the injured person. This element, however, is included only for iniured persons and then only if tney were employed at the time of the accident,which may be "wageslost." This procedure somewhat of is as assumed an approachto getting with respectto the usual practice in an oddity when consideredin its entiS,4ty of economystudies highwayimprover(ent. "wageslost" are includedregardless First considerthe personinjured. His of whether or not he actually suffered a decreaseof income becauseof the accident. The fact that he may havebeenpaid his regularwageduring his period
of recovery from his injuriesbeci is not considered. Further, he I to ment or accidentinsurance Pd is The secondconsideration I may not be employed at wageq societyasa whole. SuchPersons al service, to community functii choresat home. At leastfor mad as economicsystem is the time of tr Third, there is a generalthcd for work, some worthwhile econi empl the fact that other persons. necessary. Thesepersonsmay sl other work to a later date. ForsI just remains undone until hc I increasedefficiency of those at I Lastly, analystsof the econ valued the travel time of all pcnq if one minute of time is savedPcr minuteis multipliedby the numb( numbq per minute for the average yearly value of the reducedtrav{ basis,it is just as logical to weh regardlessof devotedto accidents not. injuredor , The items I to 4 in this groq taken by a wide group of individrl his time devotedto the aspectn d could be gotten together for thcj be considerable.The times arc complexities the job; yet thd of systemand to the individualsas I or an intersection by eliminatin3| of time should be recognized, should know that thc'n accidents of consequence time consumed and Time Consumed Cost to cost of traffic accidentsso far
site and time of accident.
(2) speed changes, idling motor, (4) extra tire tread wear, tirc etc.,and (5) a expenditures, of three factors:(l) dclays
Traffic
Accidents
373
of recoveryfrom his injuries because sick leaveor generosity his of of emproyer is not considered- Further, he may have receivedcompensation from employment or accidentinsuranceto partially offset any wagesactually not received. The secondconsideration that many personsinjured in a traffic accident is may not be employed at wages, but do perform a desirablefunction within societyas a whole. Suchpersons ma] be donatingtheir time to charity,to hospital service,to community functions,and the like. not counting services and chores home. At leastfor manysuchindividuals at their time is asvaluable the to economic system is the time of a wageehrner. as Third, thereis a general theorythat whenan employed person doesnot show for work, someworthwhileeconomicproductionis lost. This theory negrects the fact that other persons, employed not, usuallystepin and do whatever or is necessary. Thesepersonsmay sacrificesomeleisuretime or they may postpone other work to a later date. For short periodsof a day or so,often u p".ron', *o.k just remains undone until he returns to work. In many work situations, increased efficiencyof those at work makesup for the absentinjuredperson. Lastly, analystsof the economyof highwayimprovements havegeneraily valuedthe traveltime of ail persons rravehng a certainprice per hour. Thus at if one minuteof time is saved per vehicre a change highway by in design, one this minuteis multipliedby the numberof vehicles year,thenby per the valueof time per minutefor the average numberof persons car, say 1.6persons, getthe per to yearlyvalueof the reduced traveltime. If traveltime is to be evaluated this on basis,it is just as logicalto evaluate the samebasisthe on time of all persons devoted accidents to regardless age,employment, of economic status, whether and injured not. or The items l to 4 in this group are a f'ewor the manytime-consuming actions takenby a widegroupof individuars noneof whom is monetarily compensated for his time devotedto the aspects the accident. If all such time of consumption could be gottentogetherfor the countless peopleinvolved, aggregate the would be consioerable.The times are not gotten togetherbecause of the size and complexities the job; yet thesetimes are just as valuable of to the economic system and to the individuals is the l0 seconds I minuteper vehicle as or saved at an intersection by eriminating stop or a slowdown. Here or a againthis concept of time shouldbe recognized, users results studies and of of of the costof traffic accidents shouldknow that the repofed valueof ..wages lost,'is not the realtotal consequence time consumed of becaude accidents. of Time Consumed and Cost to Genelrar Traffic Because Accident. one sizable of cost of traffic accidentsso far not investigated that incurred is by traffic at the site and time of accident. Thesecostsare primarily found in five factors:(r) speedchanges, idling motor, (3) extra travel distance (2) because rerouting, of (4) extra tire treadwear,tire chains, fire extinguishers, chains, tow and personal expenditures, etc., and (5) a greater traveltime. Extra travel-lime composed is of three factors:(l) delays(stopped time), (2) slowerspeeds, and (3)reroutinq.
374
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Accidents
Accidents of insurancewould be abou{
onheavilytraveledroutes,accidentsatrushhourscanresultindelaysatthespot of vehicles' of a few minutesto hours and involvethousands cited' A rear-endcollision One referencein the literature tl5-541 may be Northwest Freewayin San on the happenedat 5:21 p.m', August 17, 1962' Antonio,Texas.Theaccidentdidnotstoptheflowoftraffic'butdidslowit downuntilthetwocarsinvolvedweremovedoffthetwo-lane,onedirection 5l minutes'affectedl'440 pavement. In all, traffic was delayedsomewhatfor ot 66'2 vehicle-hours' The vehiclesfor a total delay of 3,971vehicle-minutes' was 47 seconds. The maximum normal travel time to, it e distance involved traveltimetakenbyanyonevehicleuntiltrafficregaineditsfreeflowwas 8.T5minutes.Thenormaltrafficflowpastthesiteofaccidentwasabout50 vehiclesper-minute.Notreportedisthenumberofvehiclesthatmayhaveturned at off the freewaY a Prior exit' Unclassifiedand Insurance-GroupE Courtactionsttequentlyawardinjuredpersonsorsurvivorsofthefatalities dollardamagesinexcessofallknowncosts.Insuchcasestheexcessofthe a justifiable chargeagainstthe accident' awards abovethe known costsbecomes Theseexcessawardsareconsideredacostdespitethe|actthattheyareabenefit person or survivorsof the above costs to the recipient, generally the injured fatally injured. Funeralcostsarenotincludedasacostoftheaccidentonthegroundsthat there is justification of including they are inevitablein the long run. However, at the date paid and a similar the differencein the presentworth of funeral costs deceased' of paymentat the future dateof normal life expectancy the for payment of the costsof traffic Undoubtedly' many personsresponsible a c c i d e n t s m u s t b o r r o w m o n e y f o r t h i s p u r p o s e o r w i t h d r a w m o n e y f r o mthee r e s t int Ioan or the investmenis. In suchcases interestpaid on the or dividend_paying returnforgoneonthewithdrawninvestmentisacostchargeabletotheaccident. Thestrain,anxiety,andfatigueresultingfromanaccidentmaybringon be the causeof a secondaccident' illness to others than the accideni victims or Althoughsomewhatdifficulttoferretoutandtoprove,sucheventsareknownto havehapPened' etargeitemoftrafficaccidentcosttotheroaduserisliabilityandproperty policy holders; thosehaving accidents damageinsurance. Premiums are paid by not equal premiums paid' The have their claims paid. But claims receiveddo differenceisthatsumrequiredtopayforoperatingtheinsurancesystem. s a l a r i e s , c o m m i s s i o n s , . " n t r , c l a i m a d j u s t i n g , c o u r t e x p e n s e s ' oarc r a t i n g pe All thesecosts and communications are paid for out of premiums' expenses, usuallylumpedundertheheadingofinsuranceoverhead.Inlg65thegeneral vehicle insurancewas estimated administrative and claim settlementcost of motor accidents'this overhead at $2.850,m0,000tl5-36, p' 5l' Basedon ll'000'000
For both of these two fod of their net overhcr{ Much more needs to b stid,{ to other authors to covcr! vehicle insurance has boC . State legislaturcs en{ oners and rate rWu&| Some states tic b{ of maintaining tund1l
tt"tl il- ComPulsorY dher factorsarcst eod rler manYranifiGd-{
Ady,Mkl'l J lb aggattc bqif, d
d'r.
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Accidents
375
cost of insurancewould be about $ 245 per accident and about $ 40 per registered vehicle. One insurance cost item not directly a cost borne by traffic accident victims or vehicleownersis the net costof workmen'scompensation insurance. Accident and income compensatoryinsurancepolicies are held by many personsindividually- For both of these two formi of accidentand compensatory insurance some proportion of their net overhead costs is a just charge against traffic accidents. Much more needsto be said about motor vehicle insurance,but we leavethis subject to other authors to cover more appropriately. Mention can be made that motor vehicle insurancehas becomean important social and economicfactor in society. State legislatures and congress are involved and special insurance commissionersand rate regulatory bodies are involved together with public hearings. some states tie insurance coverage with vehicle licensesfor the purpose of maintaining funds for payments when the responsible person is uninsured. compulsory insurance is also a subject of public concern. when all these and other factors are considered,it is easily recognizedthat motor vehicle insurancehas many ramifications involving costs,public policy, private business, and individuals. Anguish,Anxiety, Misery, and Suffering-Group F one of the disagreeableaspectsof injury and fatal traffic accidents is the consequenthuman anguish, anxiety, misery, and suffering. Theseconsequences are both mental and physical; they affect the injured, the relatives and friends of the injured, the passersby,and eyewitnesses. Individually and collectivelywe are willing to pay a high price to avoid theseconsequences, what price has not but been determined. Humans do not want to inflict pain, not even to animals. Here again there is an element of personal preferencerather than of economy. Perhaps there is someeconomiccost to anguish, anxiety,misery,and suffering becausesuch factors affect production at work and safety in traffic. A deeply worried person suffersdecreased attention to his work and to motor vehicle driving with consequentdecreasedproduction and increasedtraffic accidents. To price thesetwo unfavorableconsequences oftraffic accidents in is order for economy studies,but impractical. The anguish,anxiety,misery,and suffering that result from traffic accidentsbecome collectively another nonmarket item in the economicanalysisof alternativehighway improvements to which subjectivejudgment may be given as judged to be appropriatein each individualproposal. These human factors are what concernmany of the public and many public officials. These are the elementsthat justify accident reducing measures that cost more than the expected reductionin accidentcosts. Thereis no known way to put a price, cost, or value tag on these nonmarket consequences traffic of accidents. They becomestrictly a matter of management decision.
.i
j
I
376
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Accidents
l
of of It is to be noted that the sacrifices normal pleasureand dutiesbecause item' in are accidents placed thisgroup,alsoasa nonmarket G and Received Normal Cost Avoided-Group Bene{its only in terms The tendencyof most personsis to think of traffic accidents no attention is given to monetary benefits from of gross cost. Practically savingsfrom accidents. It is as logical to consider the monetary gains or Gains will offset part of the costs. court awards accidentsas it is the costs. ofdamageandcompensationaresometimesconsidered,butotherwisethegains are not usuallYmentioned. they are usuallyminor in dollarvalue' because The gainsare not assembled hard to locate persons'and are of a nature numbersof with scattered associated let difficult to determine aloneto price. intended here that these gainsshould be soughtout There is no suggestion costsand and priced; the generalobject of all economystudiesis to get at the net are somegainsto offset someof the costs net benefits,so recognitionthat there thereis coststudies, with accident is in order, for the samereasonthat, generally, are costs not assembled. givento the factthat all ofthe recognition main in is The handling of the living costsof the deceased discussed the disability' on ahead deathandpermanent section Services OperationrGroupH and Governmental All governments-city,county, state, and federal-carry on many activities directly related to traffic accidents. Although not easily assignedto specific and operationsare a part of the total costof the accidents, costsof theseservices traffic accidents. of In this grouparetwo mainelements major magnitude. They arethe court and the policeand traffic officer operations' and legaloperations Group H includes some of the items of traffic accident costs which are borne by the public at large not including highwayfunds. To a certainextent' taxesin with general are road usertaxes,fees,and licenses usedin combination ofthe costoftraffic accidents. support and reporting,and accidentreporting Courtroom costs,police investigation of are and analysisby the severalgovernmentalagencies examples generalcost The court costs involvedin traffic accidents. not borne dirfctly by thosepersons do involvedin accidents thosepersons by which may bd assessed the court against responsible not pay the whole of the direct and indirect cost to the public agency for the traffic court. From the public viewpoint, it is not likely that thesecosts have beenfully determined. The traffic police and highwaypatrol devotemuch of their time and travel to traffic accidents,which time and travel would be did utilizedif accidents not occur. otherwise are attended on the site by many public and private rescue Many accidents personnelwith specialequipment. Only certain of the costsof and emergency these on the site operations may be paid for directly by the accident victims or Items 7. 8. and 9 idering societyas a there is no tax loss responsibility.
These governmental
to traffic accidents,
Activities to Redue tb The cost of accidents measures whidr
oot a part of accident
of the total accident those listed in this group I aggressiveptograms, i have over the yC I holding down overall gn rpecifi u l j p o r I u n l a t e s tforj o { F U l l t u c opportunities r l The U.S. Department d first trial solutionsof{ 91. The programs, cr{
l. Improvedriver liccnd 2. Improvedriver trainl 3. Reduce driver drintii 4. Reduce pedestrian i{ 5. Increase seatbelt usc 6. Improvedriver envin 7. Useof improvedrcstr t. Increase of impr{ use 9. Improveemergency ! Eenefit/cost ratios ranj seat-belt use. Tt 'y and highly t{ of methodology rd to reducetraffic eC
'{ AND PERNd
How to treat death anl offered r-oom for difrci personswho die as e
Traf{ic
Accidents
377
vehicleowners. The 'remainder the costsare borne by the public treasuryor of by privateservices. Items 7, 8, and 9 are questionable,depending upon one's viewpoint. consideringsocietyas a whole, tax incomes equalto public expenditures in are so effectthere is no tax loss from incomesnot earned. iust a redistribution but ofthe t a xr e s p o n s i b i l i t y . Thesegovernmentalservicesand operationscover a group of costsdirectly relatedto traffic accidents, which havenot beenincludedin reportsof accident but costs. Activitiesto Reduce Numberof Accidents the andTheir Severity-Group I The cost of accidents in effectreducedby accident is preventionand accident reduction measures which are part of normal operations. Although thesecosts are not a part of accidentcoststo usein economystudies, they are ofinterest and a part of the total accidentpicture. without accidentpreventionactivities, such as those listed in this group, yearlyaccidentcostswould be far greater. Active and aggressiveprograms, efforts, and attention to accident prevention and reduction,have over the years been highly successful reducingaccidentrates in and holdingdown overallgrowthof the gross programs costs. These themselves are specific opportunities economy for analyses. The U.S. Department of Health, Education,and Welfaredeveloped 1966 in somefirst trial solutionsof the economyof nine different traffic safetyprograms -15-491.The programs, evaluatedon a national basis, include the following: 1. Improvedriverlicensing 2. Improvedrivertraining 3. Reduce driverdrinking pedestrian 4. Reduce injury 5. Increase belt use seat 6. Improvedriverenvironment 7. Useof improvedrestraintsystems additionto lap belts) (in 8. Increase ofimproved safetydevices motorcyclists use by 9. Improve emergency medicalservices BenefiVcostratiul_ranged 1.7 for improved driver training to 1,351 for increased seat-belt use. This reporttl5-491isacknowledgedbytheauthorstobe exploratory and highly tentative. However, the report is good reading as examplesof methodologyand of the factors involved in predictingthe result of programs reducetraffic accident to ratesand their costs. DEATH AND PERMANENT DISABILITY
How to treat death and permanentdisability in accidentcost reports has long offered room for different procedures. That the probable future income of thesepersonswho die as a result of traffic accidents whoseprobablefuture or
378
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Traffic
Accidents
incomesare materiallyreducedbecause work-disabling of injuriesrepresent some sort of cost chargeable accidentsis generallyaccepted. In principle, a fatal to accident or a permanently disabling injury accidentneedbe treated no diflbrently than other accidents. The factor of time is present in all accidents and varies only in its duration. VIEWPOINT TOWARD DEATH AND PERMANENT DISABILITY The cost of fatal injury accidents and accidents that result in permanent disbility may be viewed from three aspects:(l) the cost of property damage, (2) medicalattention.and other direct expense, the worth ofa life to relatives and friends viewed from sentiment and love, and (3) the economic loss becausea producing person is removed from his role in society as a producer. The compensation for body disfigurement may be included with this third factor. The commodity, service,and all cash costs associated with the fatal injury accidentcall for treatmentno differentthan for other accidents. The worth of a life to those personswho have a personalcare is without a sound basis for estimating. The general practice is to save a life at any cost because human life is valuedhighly as life and not because one'scontribution of to societyor to economicdevelopment. Courts and juries have placedvalueon life, but generallythe basisofthe valueis not stated. The basiscan be sentiment, presentworth of future income,or any combivalue as support to dependents, nation of thesethree factors. The value of human life as life, however,is not a cost in the sensethat expense suffered. Since there is no basisfor statinga is value as support to dependents, presentworth of future income, or any combination of thesethree factors. Likewise,economystudiesof highwayimprovements shouldnot includethe value of life as a sentimental factor.but onlv as an economic factor. ProbableFuture IncomeForgone When life and death are viewed from an economicfocus,rather than from sentiment, thereis a basisand a logic of placinga price on death. .. A traffic fatality removesthat person from society,and, therefore,society movls..into the future without his contributionsand burdens. In this respect, death is fundamentallythe same as temporarydisability to work; the difference being that death brings permanentabsence from work and temporarydisability is for one day or other comparativelyshort period. By logic, then, when a gainfully employedperson is injured in a traffic accidentand his wageslost are reported as a cost of the accident,the wageslost by a fatality should be also reportedas a cost. The time period of probablefuture incomecould be fixed by humanmortality and life expectancy tables. If wageslost were to be computed on a lifetime basis,one uncertaintyand one corrective factor have to be considered. A person's current wage rate,
especially youngin age,{ if some estimate shouldbe rnrd o l t h e t i m e v a l u eo l * o n " y , { he remainalive-would havetd I present worth. This reasoning has basic{ statedin the discussion oftid lost for only thosep"rsonsJ valueof time for all persons if probablefuture earnings ar{ should be reportedfor all fd dayoftheir death. I ProbableFutureLivingd
But in view of the prinj in order to considerttre gel oost or net gain can bc { machine. This is the viewpo theory of lost production. I nachine in profitable prod I person in a productiue*od lcalth cost money; this cosf i b society. When a pcrl{ frt person in the futthe. Tl society of a living persol a measure of his pro{ ining the personin sod Merits of the Concep of {
D u b l i na n d L o t k al l 5 - l 4 l { ' published in 1946. tr to economystudies. A as the presentwci his contribution to soc'rd and other expenses (ari offers a reasonablc{ ) ives in which fatalifl has the advantagcd as an individualand d placing a value on travd I doesresultin an estid to those-persons I who
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cspecially if young in age, would not remain constant throughout expected life, so rcme estimate should be made of his future earnings year by year. But because of the time value of money, the probable future earnings of the deceased-should he remain alive-would have to be discounted at an appropriate vestchargerate to presentworth. This reasoning has basic logic, but two factors are yet to be considered. As stated in the discussionof time and wageslost, there is no logic to including wages lost for only those persons gainfully employed at the time of the accident; the value of time for all personsinvolved should be included. Likewise with death; if probable future earnings are to be reported as a cost ofa fatality, then this cost should be reported for all fatalities regardlessof their employment status on the day of their death. Probable Future Living Costs Avoided But in view of the principle that all consequences are to be consideredit is in order to consider the gains from death along with the costs, so that the net @st or net gain can be determined. Man may be viewed as an economic machine. This is the viewpoint, actually, when lost wages are computed on the theory of lost production. lt costs money to power, operate, and maintain a machine in prolitable production. Likewise. it costs money to maintain l person in a productive work status. Food, clothing, shelter, education, and lcalth cost money; this cost is essential to life and to keeping a person useful to society. When a person is killed, society saves the expense of sustaining lbat person in the future. Therefore, economically speaking, the present worth to society of a living person is the present worth of his future gross earnings (as a measure of his productivity) less the present worth of the cost ol naintaining the person in society for the full period up to death. Merits of the Concept of the Economic Man Dublin and Lotka I | 5- 14I develop this concept in their "The Money Value of a Man," published in 1946. There is need for an up-to-date development applicable to economy studies. A net value of man as an economic machine when developed as the present\arth of his probable future net income (as a measure of his contribution to society) less the present worth of his probable future (as a measureof the cost incident to his contribution to living and other expenses society) offers a reasonable economic base for comparing highway investment alternatives in which fatalities and permanent disabilities are a factor. This scheme has the advantage that it does not require placing a value on a life simply as an individual and the scheme is in harmony with the general approach of placing a value on travel time. The net present worth as calculated by this method does result in an estimateof what would be the net presentvalue of a wage carner to those personswho sould benefit in the future from those wagesshould
3ao
Traffic
Accidents
Traffic
Accidents
they continue. The method avoids, however, using the court awards on account of death which awards do not result from any known systematic procedure of arriving at an answer. Court awards tend to come out of a mixture of sentiment, economics,and the ability to PaY. CALCULATING THE NET ECONOMIC WORTH OF A PERSON Application of the concept of the economic man to traffic accidents gives rise to some practical questions and procedures worthy of discussion. There are five basic factors to establish: (l) wage, salary or fee, income for each age for the (2) full period of working years by trades and professions, ageofretirement or age beyond which no further wage or salary would be earned, (3) yearly cost at each age of maintaining the individual in a working status,(4) probable life expectancy for persons of all trades and professions and at all ages, and (5) the discount rate to use in calculatingthe presentworth ofyearly incomes and expenses. The total process of calculating the net economic worth of man based on is lifetime earnings and expenses somewhat involved. Only a brief discussionof t h e p r o c e s si s g i v e n h e r e . D u b l i n a n d L o t k a l l 5 - l 4 l i s a g o o d r e f e r e n c e . T h e subject is discussed in Ref. 15-49 so far as life income is concerned. Wilbur Smith and Associates ll5-42, pp. 205-2171applies the processto highway traffic accidents,but the procedure is somewhat at fault becauseofusing averageyearly income for the period of remaining life rather than on a yearly basis. Futher, the maintenance of man is used as a fixed sum of 52,000 a year age ll to full life expectancy. A variation with age is more realistic' Future Wage, Salary, and Fee Income Current annual wage and salary incomes of individuals vary principally with five factors-age, education, type of employment or profession (trade, craft, art or skills), individual abilities, and geographical location. Income data related to these factors are available from reports of the census of the United States and other economic reports. In application olthe information, it may be assumed that the future incomes of all individuals will advance or decline according tO the present incomes of persons older and in the same classification with respect to education, type of employment, and other factors. Average annual incomes can be used for speciiic ages and types of employment orprofessions. but not in the sense of an average person with respect to all factors. Nationality and sex are factors bearing on income, but these factors are largely accounted for in type of employment or profession. Earned income usually begins at about age l8 and generally increaseswith age up to a plateau where it continues level for some years. There is often a falling off in earned incomes prior to retirement, especially for manual laborers and skilled craftsmen. No allowance is made for inflation or deflation of the value of the dollar or for probable changingtechnology.
Lifetime Working ExPectancY
r o C a l c u l a t i o n f t h e P r e s e n td those years of productiveemPloY life expectancy. Active wage c{ employmc upon many individual, of Yearly Expense Maintainl
Since man is viewed as an og bt useful to society,the usefulness and fees,it is approPriateto dodl achievethe earnings. ln other si .': year of his working expectancy. will includesud The expense for health, travel to and froril{ other professional exPense,ofl insurance. Each of theseitems I individual person, though h" t4 with his education and training analysisis from the viewPointd by the legal survivors of the d costs o[ sustaining a Person ii the costs. i Income tax, ProPertytaxdl individual from his earnings{ as expensesnecessaryto mril local and state income, ProPerth taxesbecomegeneralfunds withq A personowning no taxablePrq form of rent. Where incomc ttl produced by proPertY.salcs' end rn theorl eruYc rccurity tax ir I is deducti Risk |ogas
Ufc i lsoc
Traffic
Accidents
341
Lifetime Working Expectancy Calculationof the present worth of the future incomes basedupononly is thoseyearsof productive employment professional or practice,as contrasted'to life expectancy. Active wageearnings cease between age 60 and 75,depending upon manyindividual, employmgnt, geographical and factors. Yearly Expenseof Maintaining Productivity Since man is viewed as an economicforce producing productsand services useful to society,the usefulness being measured the earningsof wage,salary by and fees,it is appropriateto deduct from his earningshis expenses necessary to achievethe earnings. In other words,net earnings what are wantedfor each are year of his working expectancy. The expense will include such items as food, clothing,shelter,requirements for health, travel to and from work, fecreation, professionaland union dues, other professional expense,education, job training, taxes, and employment insurance. Each of theseitems is supporteddirectly from cash earningsof the individual person, though he may not pay directly for all expenseassociated with his education and training when in the working class. But since this analysisis from the viewpoint of societyas a whole and not as may be viewed by the legal survivors of the deceased, is appropriate to include all the it costs of sustaining a person in his working status, regardlessof who pays the costs. Income tax, property taxes,salestax, and other taxespaid in supportof the individual from his earningsare items of expense deduct from earnedincome to as expenses necessaryto maintenanceof a working status. Once collected, local and state income, property, and salestaxes and federal incomeand excise taxesbecomegeneralfunds without identificationso may be treatedasjust taxes. A person owning no taxable property pays the equivalentof property tax in the form of rent. Where income taxesare not imposed,their equivalentincomeis produced by property, sales,and other forms of taxes and fees,so in the end and in theory everyonepays his share of taxes directly or indirectly. Social securitytax in all of its components a necessary is expense working, so it too, of is deductiblefrom income. Risk and compensationinsurancepremiums are associated with maintaining a working status so would be another item to deduct from grossincome. Life insuranceis not a necessary expense maintenance a working statusso to of its cost is not deducted. For all forms of taxes and risk insuranceonly that paid in support of the specific traffic accident fatality would be considered. Taxes paid from his income support also his family and any other dependents, their pro rata so sharewould not be deductedfrom grossearningsto get the net probablefuture earnings the deceased. of
3a2
ProbableLife ExPectancY
Traffic
Accidents
Ttaffic
Acddents
Fromthehumanmortalitytablesasusedinlifeinsurancepracticelife sex' nationality' and may be obtained iot p"t'on' at all agesby expectancies is normally greater than working type of employment. The life expectancy from employmentsomeyearsaheadof death' of retirement ;""*;" "';.;;t;; Inthoseyearsofnoearnedincomejustpriortodeathatoldagethenetproductive retiredperson' by would be negative the full amountto supportthe earnings Discount Rate Thevestchargerate,ordiscountrate,usedtotransfertheyearlynetearnings fortheremainingyearsoflifeexpectancytopresentworthshouldbebasedupon whatmoneyisworthtotheindividual,andmostcertainlywouldbehigherthan bondinterestrates,ratesearnedonlifeinsurancepolicies,butperhapslowerthan thevestchargerateusedineconomystudiesofpublicworks.PerhapsTto9 percentwould be reasonable' ENT ECON OM IC MA N-CONCLU DI N G STA TEM onthebasisoteconomics,theforegoingschemeoffersalo.gicalbasisof fatality' The calculation can be computing the cost to society of a traffic a p p l i e d t o p e r s o n s o f a l l a g e s f o r t h e i r e x p e c t a n c y o f l i f e a n d o f e aThen g s . rni negativepresentworth' Young personsand very old-personscould-have future years for living expense youni would have heavy cosf in the immediate andeducationandnoearnings'Theearningswouldbefarinthefuture,and, presentvalue. older personswould therefore, would have comparativelylow havenormallivingexpenseandperhapsbutlittlefutureincomefromproduc. tiveactivities' in the same manner as for a Permanent disability could be considered presentworth would be highly negative' fatality. For total disability, the net would be a lesser cost to society than indicating ,t u,, ."onoticaliy' death d i s a b i l i t y . F o r t o t a l d i s a b i l i t y t h e c o s t s t o m a i n t a i n t hcare'r s o n w o u l d b e e p e Retraining full-time personal exceedinglyhigh for those casesneeding persons' disabled could be heavyfor partiallybut permanently expense I t i s t o b e b o r n e i n m i n d t h a t t h e c o n c e p t o f t h e e c o n o m i c v a l u eown a n t o ofm ot:!lt-tt^t:om his -tiiott', societ\. that his *;s; ";; salarvincome-that.whichlt a measure on not includingearnings investments-ls physical)nd mental o f h i s p r o d u c t i v i t y a n d t h e r e f o r e o f h i s v a l u e t o s o c i e t y . I n t u r n ' s o c i e andu p p l i e s t y s to earning capacity of the individual the supportsn.."r,u'l to J"u"top the of status. The analysisconsists measurmaintain the individual in a productive ingthesetwostreamsofcashflow_incomeearningsandoutgoexpenses-and f i n d i n g t h e i r n e t p . " ' " n t * o ' t t ' ' I n a p p l i c a t i o n o f t h e c a l c u l a t i o n o f t hexist' so itm i c eecono personsimply doesnot value of a highway traffic fatality' an average
b necessary know at lce{ to crch individualfatality. i The general present lreflic fatalities high i
Int than to economics. Dciety as a whole will nd,
icle drivers will not do perhaps drivers valuc
ACCTDENT eol
.l
,1
l
{
Including traffi c accidi improvements requircs i and (2) the comp{ with eachalternatil for economy studies aq discussedin the followir are not availabe,brtr
OF COMPILING UilN
When determining thc cl point of view from whict,i those compiling such ao{ l l - 3 , l 5 - 2 5 ,l 5 - 4 2 ,a n d l 5 l )r, owner of damagcd 96 the cost of traffic acci{ rns and property plus o{ not have occurred witl accident cost items nl coststudyLl5-251: I l. Propertydamage I A. Damageto vchidc il B. Damageto propc{ C. DamagetoobjeArl D. Miscellaneous prog{ 2. Treatment of lnjuricr fl A. Ambulance serviocI B. Doctor and dentir{ C. Hospital and trcerr{ D. Miscellaneous mcfl
Traffic
Accidents
343
to is necessary know at least the age,sex,education,and employmentstatusof cachindividual fatality. The general present tendencyis (and perhapswill continue to be) to give traffic fatalitieshigh importancein highway design,with more thought to sentiment than to economics. But there must be somelimit of cost beyondwhich society as a whole will not go io savea life. When viewed in the light of what vehicledrivers will not do to achievesafe driving, there is a logicalconclusion that perhaps drivers value their own lives (sometimes)but not the lives of others.
UNIT ACCIDENT
GOSTS
FOR ECONOMY
STUDIES
in for Including traffic accidents the analyses the economyofproposedhighway improvementsrequires that two factors be known: (l) the cost of traffic or accidents, and (2) the comparativerate of accidents the number of accidents as associated with eachalternative be considered. The costsof accidents availto in able for economy studiesare discussed this sectionand the ratesof accidents are discussedin the following section. Costs in the form ideal for economy acceptable costsmay be had. studiesare not availabe,but by judicious selection 8,{S/S OF COMPILING UNIT ACCIDENT COSTS When determiningthe cost of traffic accidentsit is necessary determine to the point of view from which the costis to be measured. The viewpointassumed by those compiling such accident cost reports as given in Refs. l5-4, 15-19-2, viewpointof the motor vehicle !5-21-3,15-25,l5-42,and l5-50, is the combined property, and personsinjured. The basic theory is owner, owner of damaged that the cost of traffic accidentsis the money value of damagesand losses to personsand property plus other expenses connectionwith the accidentthat in would not have occurredwithout the accident. Using this combinedviewpoint, traffic accidentcost items may be grouped as follows as is given in the Illinois accident coststudyt I 5-251: l. Propertydamage A. Damageto vehicle B. Damageto propertyin vehicle struckby vehicle C. .Qqnage to objects propertydamage D. Miscellaneous 2. Treatmentof injuries A. Ambulance service B. Doctor and dentistfees C. Hospital and treatment medicalneeds D. Miscellaneous
344
3. 4. 5. 6. Loss of use of vehicle Value of time lost Legal and court exPense Damages awarded in excessof known cost
Traffic
Accidents
Traffic
Accidents
These six basic groups constitute what may be called the direct accident costs-that is, the money value of damages and losses to persons and property resulting directly from accidents and which would not have occurred had not the "resulting directly from accidents," accident happened. The use of the phrase, is somewhat misleading, because there are many other costs that result from accidents that are not included, as have been discussed elsewhere in this chapter' In the Washington, D.C., area report ll5-42 I the classificationwas slightly d i f f e r e n ta s m a y b e s e e ni n T a b l e sl 5 - 7 , l 5 - 8 ' a n d l 5 - 9 ' THE DETAILED COST ELEMENTS USED IN THE ILLINOIS STUDY
Legal and court expense it' bond. and similar costs for anj Damage.s awarded include s( in excess l the known costs. Tl o compensation for past or futur{ taken to avoid duplicating thc I the net of awards above the kno{
r
l
SPECIFIC UNIT COST OF AO4
I
In the lllinois report the following is the basis that governed the collecting of the costs: Damaged propert)) includes the damage to motor vehicles involved' clothing and personal effects, baggage and cargo within the vehicle, roadside buildings' utility poles, landscape,and to the highway. Towing serviceis included. Treatment of injuries includes all professional medical and health services, hospital care and treatment, medicines, appliances, and home treatments. These items of cost are included for fatal injury accidentsup to the time of death iost will only. Funeral and associatedcosts are excluded on the basis that such is in order to include the differencein presentworth of the occur anyway. But it cost of death based upon the date of death and the normal life expectancyofthe deceased. i L o s s f u s e o fv e h i c l es t h e l o s s o f e a r n i n g o r b u s i n e s s p r o f i t d u r i n g t h e t i m e t h e o vehicle is not available as a result of the accident. lf other transportation was available and used there is no value lost. This value of the loss of use of the v e h i c l ei s n o t t o b e i n c l u d e di n t h e v a l u e o f t i m e . Value of work time lost is included only when the person involved in the accident was a gainfully employed member of the labor force and when such incapacitation was temporary. Permanent total or partial disability is not for recogniqed. Loss of future income becauseof death is not included, not even of death. All work taken time by that time-betweenthe date of accident and date the injured from income producing activity to have the vehicle repaired,to appear in court. to Settle claims, to receive medical treatment, or for other reasons is included. The cost to a housewife who must hire help to replaceher is included' person The dollar value of time is computed at the rate of income for the specific regardless of whether the person concerned. This value of time is included, actually suffered a reduction in income or was fully or partially compensated through insuranceclaims.
From the literature,mainl; costs of traffic accidentshave I selecting accident costsfor ecod careful attentionto the specifi available, and all pertinent ff variable that broadgeneral costs TABLES OF UNIT ACCIDENT
Fortunately, traffic accidct frequency. But unfortunately, I place,cause, and consequence N accidents a soundstatistica on proposedhighway improveme particular project. route. or 3t in costsmtt differences accident being studied Gcl alternatives highwayare not to be { specific severityare available. Generd comparisoo reach a reasonable nativeunder tudy. s s The traffic accidentrecorda in a n d m o s tp u b l i s h e d f o r m a t i o n (individ number of involvements in economy studiescostsexprcl cost per accident ties in with thl say, of accidents, per millionvehi Cost Tables from the llliroh
I
The lllinois 1958accident d reported in the following tabl6New lrom Massachusetts,
litan area study-of 196445
TraJJic Accidents
345
Legal and court expenseincludes payments for legal fees, court costs, bail b o n d , a n d s i m i l a r c o s t s f o r a n y l e g a l p r o c e e d i n g sr e s u l t i n g f r o m t h e a c c i d e n t . Damagesawarded include settlementsin or out of court for only the amount in excess the known costs. The award may include known direct cost and some of compensation for past or future loss of income based upon disability. Care is t a k e n t o a v o i d d u p l i c a t i n g t h e k n o w n c o s t sa n d v a l u e o f t i m e b y i n c l u d i n go n l y the net of awards above the known cost. SPECIFIC UNIT COST OF ACCIDENTS F r o m t h e l i t e r a t u r e , m a i n l y f r o m t h e l l l i n o i s a c c i d e n tr e p o r t [ 5 - 2 5 ] , u n i t costs of traffic accidents have been compiled in a form to serve as guides in selectingaccident costs for eeonomy studies. Unit costs should be selectedwith careful attention to the specific alternatives being examined, to the unit costs available, and all pertinent factors. Traffic accident costs are so highly variable that broad general costsshould be usedonly as a last resort. TABLES OF LINIT ACCIDENT COSTS FOR ECONOMY ANALYSES Fortunately, traffic accidents do not occur with regularity and in high frequency, But unfortunately, becauseof their irregularity, variability in type' it place, cause,and consequence, becomes most difficult to assemblethe costsof accidents on a sound statistical basis in a form reliable in their application to proposed highway improvements. What is wanted are the accidents for the particular project, route, or system under study and in such detail that the differences in accident costs may be had for the differencesin the improvement alternatives being studied. Generally, the specific accident cost data for the s p e c i f i ch i g h w a y a r e n o t t o b e h a d , b u t p e r h a p st h e p a s t n u m b e r o f a c c i d e n t s a n d severity are available. General average accident costs can then be applied to reach a reasonable comparison of the accident cost factors between the altern a t i v e su n d e rs t u d y . The traffic accident records on file within a state, city, or other jurisdiction, and most published information will give the number of accidentsrather than the (individual vehicles involved in accidents). Therefore number of involv\nts in economy studies costs expressedin dollars per accident are preferred. The cost per accident ties in with the rate ol accidentsthat is often given in numbers oiaccidents, say, per million vehiclesor per milllion vehicle-miles. Cost Tables from the lllinois and Other Studies T h e l l l i n o i s 1 9 5 8a c c i d e n tc o s t s t u d y l l 5 - 2 5 1 i s t h e s o u r c e o f t h e c o s t d a t a reported in the following tables. This study is more recent than similar reports New Mexico, and Utah. The Washington, D.C., metropofrom Massachusetts, litan area study of 1964-65 ll5-42j is not used because all the costs are
3aG
Traffic
Accidents
Traffic
Accidents
reported for numbers of involvements rather than for the number of accidents. Table l5-l offers general data to give the reader some orientation of the magnitude of the total accident picture and the general ratios of certain factors. The traffic accident cost in Illinois to vehicles of Illinois registry in 1958 at 1966 prices was $346,063,333,which amounts to $ 130 per vehicle registered and I .21 cents per passenger car-mile and 0.45 cent per truck-mile. In urban places there was a passenger car traffic accident for each 23,000 miles of travel and a truck accident for each 22.000 miles of travel. The rural travel resulted in one TABLE I5-I RArrosor SevEnrrv TnepnrcAccrDENTs or VtstcI-Es,1958 IN REGTSTERED ero Cosr penAcclDENT ILLINotS-ILLINors (CostUpdatedfrom 1958 1966 a Factor of 1.25) to by
Item and CIass Vehicle of l. Numberofaccidents Passenger car Truck . Total .. 2. Accidentsper fatal injury Passenger car Truck . Total .. ofall accidents 3. Percentage Passenger car Truck . Total .. 4. Costofaccidents Passenger car Truck . Total .. 5. Ratioofcosttofatal injury cost Passenger car Truck . Total .. 6){ercentage of total costs Passenger car Truck . Total .. 7. Costperaccident Passenger car Truck . Total ..
Soqrce: Ref. l5-25.
Fatal Injury
Nonfatal Injury
Property DamageOnly
Total
I,169 220 I,389 1.00 1.00 1.00 0.l2 0.02 0.14
103,306 9,273 rt2,579
755,87 I n2,228 868,099
860,346 tzt,72l 982,M7 735.97 553.28 707.03 87.61 t2.39 100.00 $323,462,Ot9 22,60 I,555 346,063,333
88.37 42.t5 8l .05
646.60 510.13 624.98
10.52 0.94 I 1.46
76.97 I 1.43 88.40
$9,869,882 $ t68,894,225 $ 144,697 ,9t2 12,676,309 8,406,034 t,519,2t2 157,374,2t2 I I,389,095 t77 300,026
car traffic accidentI passenger milesi for each109,000 accident For economYstudies,TaH I to as cidents related Passenge arrangement. The intersa lane ly rather than within each lal accident the more lanes of trl accident)and more costly or highways. The same classificationof ! Table l5-3 where the accll in thesetables the "not sPeciflro group. Some idea of the relativd may be gained fi intersections First, thc { be observed: should rate of accidentsbased uPon I the traffic volumes are unknol accidentsis too few to afford rd Table l5-5 is a helPfultail the three severitygroups thc c to vehiclesis high in all high for fatal injurY accidentt The involvements Per are more vehiclesinvolvcd that accidentsinvolving about 6 percentof the in certain categories, produce a reliable is of accidents givenin THE ILLINOIS A
1.00 1.00 r.00 2.85 0.44 3.29 r8,442 6,905 8,200
l7.lt 5.53
lf.)/
14.66 8.34 13.82
32.77 t4.87 30.39 93.47 6.53 100.00 $376 186 352
Tables l5-7.
cost element Washingtoabe explai included some I
48.80 2.43 5t.23
41.82 3.66 45.48
of
$I,635 906 l,5?5 $1 9 l
n2
l8l
net to
Tnaffic
Accidents
3A7
passenger car traffic accident for each 68,000 miles of travel, and one truck accident each109,000 for milesof travel. For economystudies, Table I 5-2 may be usedas a guideto the costof accidents related passenger as to cars,trucks,urbanand rural highways and traffic lanearrangement.The intersection accidents, unfortunately, shownseparateare ly rather than within each lahe arrangement. Accidentsare more costly per accidentthe more lanesof traffic there are (probablymore involvemenrs per accident)and more costly on rural highways(higher speeds) than on urban highways. The sameclassification type of highwayas given in Table l5-2 is repeate.d of in Table 15-3where the accidentsare classed highway system. In both of by thesetables the "not specified"accidentsare mostly in the unreportedaccident group. Some idea of the relative cost of accidentsby type of traffic control at intersections may be gained from Table l5-4. In using this table, two cautions shouldbe observed: First, the number of accidents reporteddoesnot indicatethe rate of accidentsbased upon exposurebecause the number of intersections and the traflic volumes are unknown, and second,in some categories number of the accidents too few to afford reliableaverage is costsper accident. Table l5-5 is a helpful table in economystudiesbecause showsfor eachof it the three severitygroups the cost per accidentfor each cost element. Damage to vehiclesis high in all three categories. Legal and court costsare especially high for fatal injury accidents only $ 0.99for propertydamageonly accidents. but The involvements accidentin Table l5-6 show that on the average per there are more vehiclesinvolved in an accident urbantraffic than in rural traffic. and in that accidentsinvolving two or more trucks in the sameaccidentoccur in only about 6 percentof the truck accidents. In usingthis table it shouldbe notedthat in certain categories, especially trucks, the number of accidents too few to for is produce a reliable averagenumber of involvements accident. The number per of accidents givenin Table 15-4. is THE ILLINOIS AND WASHINGTON,D.C., AREA REPORTSCOMPARED Tables l5-7, 15-8,and l5-9 comparethe relativepercentage cost for each of cost element as reported in the 1958Illinois urban accidentsand the 1964-65 washington,D.C., for cannot frea study. The reasons someof the differences be explained from ififormation the published in reports. The washington report includedsome cost elements not found in the lllinois report. Illinois combined someitemsreportedseparately the Washington in study. of striking significance the fact that the washington report showsthat the is net presentworth of probablefuture earningsof the deceased persons amounted to 90.8 percent (Table l5-7) of the total cost of fatal injury accidents. of equally striking significanceis that in Illinois the legal action costswere 66.g9 percentof the total costof fatal injury accidents compared only 3g.43percent as to
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TABLE 15-6 pER oF LLrNots NUMBER VEurclesINvolvgD AccTDENT-I
AcclDENTS INVoLvING VEHICLESoF ILLINoIS REcIsrnv.
Passenger-CarAccidents
39s
I958 Truck Accidents
Type of Highway
Fatal lnjury
Nonfatal I njury
Property Damage Total Only
Fatal Injury
Nonfatal Injury
Property Damage Total Only
Urban Traffic Accidents I ntersection Nonintcrsection: One-way streets with One (raffic lane Two traffic lanes Three or more traffic Ianes Undivided highways (twlway) Two traffic lanes Three traffic lunes Four or more traffic lanes . . . Divided highways with Four traffic lanes Six or morc traffic lanes Not spccified Total ... . . . . . . with
t.429
| .698
l .695
1.696
r.m0
1.041
1.047
1.046
|.000
2.006 2.006 |.9t5
r.878 t.5t8 l.334
|.882 r.523 L153
t.000 r.000 r.007
|.000 t.000 t.242
1.000 1.000 l .t 9 4
1.226 2.500 t.284
| .441 t.248 l.583
t.492 1.5t6 1.610
| .487 t.501 | .607
r.029 r.000
r.032 1.000 1.042
t.096 r.000 | .039
| .093 1.000 1.039
|.t61 t.400
I .750 Ll6l 1.929 t.606
1.99'l 2.108 1.080 |.574
r.952 t.'t9) | .081 t.578
r.000 1.000 t.0ll
1.076 t.000 t.000 r.035
t.016 1.008 | .032 t.060
t.020 r.008 1.029 t.059
t.314
Rural Traffic Accidents lntctscclron Nonintersection Undivided highways (twcway) with Twofafficlanes......... . T h r e e t r a f f i c l a n e s. . . . . . . . Four or more traffic lancs Divided highways with Four traffic lanes Six or more traffic lancs . . . . Not specified Total . . . .. .
L552
L891
t.664
t.7t9
. l09
r.073
1.024
t.010
L240 1.556 1.556
1.322 2.0-17 1.564
|. 2 l l L500 1.262
|.224 r.504 1.299
t.121 1.000 t.il l
1.052 1.075
1.020 t .t 8 9
t.024 t.000 t.l?l r.069 r.000 1.000 L019
2.500
l.142 r.329
2.000
1.496 L129 1.075 r.307
r.000 r.000
L238
|.04'l L000 1.000 | .025
L075 1.335 t.530 t.2'16
1.000 r.l13 1.061
Soarce; Ref. l5-25
for Washington, when the future income and funeral costs are omitted. The Washingtoncost for property damageto the casevehicle was 24.53percentas that c o m p a r e do l l . 3 l f o r l l l i n o i s . T h e s e v a r i a t i o n s a n d o t h e r s a r e f u r t h e r p r o o f t and are the costsof traffic accidents still in the unknown realm and all estimates compilations contain factors of personal judgments and statistical quality shortages. Attention is called to the inclusion of funeral costs (Table 15-7)in the Washington study. This item should not be included in economy studies with because it is an item of certainty at some future date not associated highway accidents.
396
Traffic
Accidents
Traffic
Accidents
TABLE I5.7 D.C', FoRTHEWASHINGToN, AREA, FerAt-lNrunvTRAFFICAcclDENTCosrs REpoRTED VEHTCLES IN UnsrN ACCIoTNTSILLTNOIS-ALL Coupnnpnro rHE 1958 1964-1965.
Illinois Direct Costs
Cost Elemenl Percent of Total
I
R E p o R T E D N o N F A T A r . I N . n J R yT R A F F l q 1964-65. CoMPARED ro rHE 195t,
D.C., Area, Washington, Direct Costs
Percent Dollars ofTotal Percent w/o Future Incotr and Funeral N u m b er o l : Property damage lnvolvements l
Dollars
N u m b e ro f t
Involvements
Accldents ...
. 690 ..
210
Accidents - . ..
Propertydamage 328,830 v l. Case ehicle 4,919 v i 2 . P r o p e r t yn c a s e e h i c l e 12,329 objects . . . 3. Outsidevehicle-other 265 4. Miscellaneousdamage Depriveduseofvehicle 17,596 b 5 . L o s tu s e y o w n e r . . v r 6 . L o s so f c o m m e r c i a le h i c l ee n t a l s Excluded C . W o r k t i m e l o s.t. . . 9,442 7. Ownevdriver Excluded 8 . B yo t h e r s D Legalactions t'7 9 . L e g l l i i n dc o u r tc o s l s . . ,779 I t e m2 3 abovecosts . . 10. Damages:rwarded group . . . . propertydamage 391,r60 E . Subtotal, Injury F . Personal 4,280 I l. Ambulance Elsewhere . 12. Othertransportf,tion I 05,703 | 3 . D o c t o ra n dd e n t i s t . . Elsewhere n 14. Privilte ursing . 238,436 . 1 5 . H o s p i t l l i z a t i o n. . . . 1 6 . D r u g s . a p p l i a n c e s. . e.t.c. . . . Elsewhere 6,5' 72 i e 1 7 . M i s c e l l a n e o uts m s . Excluded | 8 . F u n e n te \ p e n s c s l g 3 5 4 , 9| 9 il G S u b t o t ap,e r s o n an j u r y r o u p . . . . . . l H Time facl,ofs 21 6 , 8 3 8 1 9 . V d l u eo f t i m e l o s tb y i n j u r e d . . . . l o 2 0 . V a l u e f t i m e l o s tb y o t h e r s . . . . . E x c u d e d v .. . 2 1 . S p e c i a l d o m e s t i c s e r . .i.c e.s Elsewhere 2l 6 , 8 3 8 L S u b t o t a lt,i m e f a c t o r s J . L c g a la c t i o n s . 584,642 2 1 . L e g r lc n d c o u r t aboveknown 23. Damages awarded l,360,959 costs . . I ,945,60 I l K . S u b t o t a ll.e g a r c t i o n s wonh olfuture income Excluded 24. Net presenl 2,517,430 costs L. Subtotal. injury and associated 2.908.590 M . G r u n dt o t a l . . .
Soarce. Re[s. l5-]5 and l5-42
lt.3l 0.l7 0.42 0.01 0.61
243,036 4,996 3,962 il3 822
1.90 0.04 0.03 0.00 0.01
24.53 0.50 0.40 0.01 0.08
I . Casevehicle 2 . P r o p e r t y i n c a s ev e h i c l e 3 . O u t s i d e v e h i c l e s - o t h e ro b j e c t s . . z l . M i s e el l r n e o u s d r n r a g c B . D e p r i v c d u s eo f v e h i c l e 5 . I o s t u s e h r r r r rn c r 6 . L o s s o f c o m m e r c i a l v e h i c l er c
0.32
| 8,498 264 l 2,084 700 284,47 5 5.326 2,056 99,069 3,459 l03,595 3,81 I 4 rR5
I Rq t])
0.14 0.00 0.09 0.01 2.22 0.04 0.02 0.77 0.03 0 . 8| 0.03 0.03 |.4'7 3.20 0.49
l .87 0.03 t.22 0.07 28.7 | 0.54 0.21 10.00 0.35 r0.45 0.38 0.43 22.36 6.40 4.05 0.04 10.50 3 5 70 2.73 38.43 7l.29 100.00
W o r k t i n r co s t l 7. Owner/driver 8. Byothers . . Legal ctions a
9.
F
0.61 13.45 0.15 3.63 8.20 0.22 12.20 7.46
Legulund court
10. Damages awlrded above costs S u b t o t a l , p r o p e r t y d a m a g eg r o u p
F P c r s o n a li n j u r y 12. Othertransportation l - 1 . D o c t o ra n dd e n t i s t . . 1 4 . P r i v a t e n u r s i n. . . . .g 1 5 . H o s p i t a l i z r r t i. o.n . . ,
1 6 . D r u g s .r p p l i a n e c sc t c . . . . . . . - . . .
4l 0,833 63,456 40,1 | | 434 104,001 353,772 2'7.097 380,869 l l , 6 3 9 , 8l4
r 0.3 0.00
0.81 2.76
1.4; 20.t0 46.79 66.89
1 7 . M i s e c l l a n e o ue m s . it s 1 8 . F u n e r ae x p c n s e s l G . S u b t o t a lp e r s o n a l j u r yg r o u p . . . . . , in H . T i m ef a c t o r s 1 9 . V a l u e f t i m e l o s tb y i n j u r e d . . o 20. Valucof tirnelost by others . . . . 2 1 . S p e c i a lo m e s t i c s e r v i c.e .s - - . d . l . S u b t o t l l , i m ef a c t o r s t J. Legal ctions a
)2. Lcgal and court costs . . . K. Subtotal legal actions 14. Net present uonh offutureinc{rE L. Subtotal, injury and associated c6ts M. Grand total ... 23. Damagesawarded aboveknown
0.21 2.91 90.80 97.'18 8 6 . 5 s I ) 515 544 100.00 r2,820,019100.00
Soarce. Refs. l5-25 and l5-42.
Traffic
Accidents
397
TABLE I5-8 D.C.,A REA, REpoRTED NoNFarnl INJURy TRAFFTc AcclopNr CosrsFonrsE WAsHrNcroN, r A U A N 1 9 6 4 - 6 C.o v p a n E o o r H e 1 9 5 8 R B A N c c r D E N rl s I L L r N o r S L LV E H T C L E S 5
Illinois Direct Costs
Cost Elemenl Dollars Percent of Total
D W a s h i n g t o n , . C . ,A r e a Direct Costs
Percent ofTotal Percent w/o Futurc Income
Dollars
Number of:
I nvolvcmcnts Accidents . .
. . 144,861 . . 92.509
. . lu.tt]O
Property darnage
2 2 , 0 6,1 l 4 ) 7 . 7 3 | 0,984,997 3 92,145 0 .r 2 13,484 l . O u t s i d e v e h i c l e s - o t h c ro b j e c t s . . 544.411J 0 . 6 8 t4-t,921 4. Miseellrnctrus rrmrge d 20,l 69 0.03 35, 88 |
| . Cr t s e e h i e l c v l. P r o p c r t y i n c i r s cv e h i c l c Deprived uscof vehicle 5 . L o r t t r s eh v o r r n c r 6 . L o s s o f c o m m e r c i a l v e h i c l er e n t a l s
,lrl.I 4 7 0.1 0.51J 0 .l 4 r.07 0.32 1.99 0 .l 3 0.83 0 .l 2 49.19 0.60 0.-32 0.t7 5.58 0.62 0.27 15.00 8.57 0.14
4 1. 7 5 0 .r 9 0.61 0.t5 l.t6 0.35 2.l5 0.14 0.90 0.t3 53.55 0.64 0.14 8.06 0 .l 9 6.04 0.67 0.29 l6.23 9.27 0.80 0.20 t0.27 8.52 |.44 19.95 46,45 t00.00
5 6 4 , 88 I e x cu d c d l 257,620 e x cu d e d l
0 . 7|
266.274 80,058 495,I 04
1) 54q
C . Worktime lost
7. Ouncr,drivcr ll. By others Legalactions 9. Legrl and court
0.032
t
5 ll , 4 1 9 57.102 Subtotol, property damagc group . . . . 2 4 ,I 0 9 , 6 2 5
10. Damages awarded abovc costs . . P e r s o n a li n j u r y I l. ,\mhulancc I l. l{. Other trrnsportx(ion Prirute nursing . . l -1. Doctor und dcntist . . 15. Hospitrlization.... . 1 6 . D r u g s . r p p l i l r n c e s . e t c .. . . . . . ... 1 7 . M i s c e l l l n e o u st e m s . i 1 8 . F u n e r a le x p c n s e s
0.64 205,804 0.07 30,676 1 0 . 1 0 I 2 . 3| 8 , 0 5 5 0.09 8.33 6.55 0.t6 I5.23 |.94 I48,287 78,9u0 t,853,129 4 3 , 19 l |,390,389 |53,973 66,034 _ . r , 7 3 3I 9 1 , 2 , l 3I , 4 0 7 r 8 4 , 80 l 45,420 2 , 3 6, 6 3 7 I 1,959,972.
76,207 elsewhere 6.629,761 elsewhere 5 . 2 0 8 , 9|0 elsewhere 206.612 l 2 , l 2 l , 5I l 9,500,608 excluded elsewhere 9,500,608
G S u b t o t a l , p e r s o n a li n j u r y g r o u p / . . . . . / H I imc factors
19. Value oftime lost by injured . . . . 1 0 . V l l g s 6 l ' 1 i l n gl o s t b y o t h e r s . . . . . ll. S p e c i r l d o m e s t i c s e r v i c.e . . . . . .s S u b t o t a l ,t i m c f a c t o r s Legal actions 11. Legal and court costs . . . S u b t o t u ll e g a li l c t i o n s . :J. Net present worth of future rncome ....
I
0 .r 8
9.49 1.87
I 1.94
|2,663,512 r5.92 2t.114.396 33 , 8 3 7 , 9 2 8 e x cu d e d l 55,460,047 19.569.6-72 26.62 42.53
J3. Damagesawardedaboveknown
L, Subtotal, injury and associated costs
u
Crand total
.Sorrce. Refs. l5-25 and l5-42.
2,630,546 I 0 . 5 7 4 , 5 9 0 ,| 8 5 18.44 I,884,941 7.58 69.70 I 2,57I ,007 50.51 100.00 24.889.062 t00.00
394
Traffic
Accidents
Traffic
Accidents
TABLE I5.9 Dlvecr' ONt-Y PnoPenrY RePonteo D'C'' A nte' 1964-65' non Cosrs rue WesutNctotl' AcclDENT Tnnrptc
CouprnEo ro rne 1958 URBANAcclDENrs llLtNots-AlL VEstcles
R^Tpof TO COSTOF
AcENcrEs-1958
Illinois. Direct Costs
Cost Element
D.C., Area Washington, Drect Costs Dollars ""'67'010 ? Percent of Total
fuanydemagc injurics bmtof e of vchiclc lto( of lam lcr rd drt rt ccts io qsdlmc
Dollars Involvements Accidents
Percent of Total
Numberof:
A.
1,22'1,952 809,855
Propertydamage 2'7,441,8M+ 93.2'l I 1 , 6 5 4 , 8 0 1 89.99 vehicle . l. Case 0.17 22,324 0.22 65,054 Propertyin casevehicle 2. 0.9'l r25,759 2.16 635,283 objects . '. 3. Outsidevehicle-other 0.34 44,572 0.04 10,750 damaf 4. Miscellaneous useof vehicle Deprived 1.59 205,373 t . 74 512,919 5. Lost usebY owner vehicle 6. Lossof commercial 39,708 Excluded rentals . lost c. Worktime r . 3 5 648,635 5 . 0 1 t97,14'l 7. Owner/drive.. '... r 0.28 35,662 Excluded 8. By others D Legalactions t.24 l6t,252 0.97 285,402 9. Legaland court 0.10 13.488 0.25 7 3 , 85 1 awardedabovecosts .. 10. Damages 29,422,2t4 100.00 t2,951,5'14 100.00 E . Grand total
*Reoortedcostsplusunreported totrl s92'259'074 costs Refs l5-25and l5-42' Soarce.
bCd
dilirri.3
EIGL..--
b -iJ-.-
..-............
presentworth of A word is in order about item 24 in Table l5-7, net earlier in this chapter' As discussed probable future income of the fatalities. cost of traffic such calculation is one approach-to determining an economic fatalities'butitscalculationisinvolved,inclusiveofmanyjudgments,andthe useda answeris affectedby the procedureused. wilbur Smith and Associates procedure||5.42,pp.ln.5-2|r7)thatislackingincorrectapplicationofcompound fatality for the interest theory. They used an averagerate ol income for each than the income for each year' For rather remaining working expectancy say professionalpersonsand other personswhose incomes increasewith age, discounted more heavily in a year by up to age 60, future incomes will be sum year summationof presentworth than will be true by usingthe meansingle time' income for eachyear of remainingworking yearly cost was used, $ 1,000to age l0 and Further, a constantsubsistence by that the costssustained a $ 2,000from age 11 upward. It seemsreasonable
Trraffic Accidents 399
TABLE I5-9A
Rnrro on TorAL Cosr oF TRAFFlc Accr DENTs
TB.!.^r::.: -O-Ir_l ose AccroeNrs AceNcr's-re58Acc,oeNrsrvr;ffi Reponieo rl'O"o.,.,o, ;il;;i;,ffiil#:;rTTlil'o*.o,rr*,
Rural Traffic Accidcnts Urban Traffic Accidents
^
Tu
Fatal Cost Item I njury
Nonfatal Injury
Property
Damage Total Fatal Injury Nonfatal lnjury
Property Damage Only
Total
Only
Passenger Car Traffic Accidents Property damage T r e a t m e n t on j u r i e s , . . . . . . . . . . i f Lossofuse ofvehicle . , . . . . . ,. . Valueoftimelost.... L c g a l a n d c o u r t c o s. t. s . . . . . . . . . . . Daroge aurds in cxm of knom cms
.m0 .000 .0@
.t 6 9
3.857 5.231 4.80'l 12.547 8.615 3.972
t.108 .003 .763 .025 .t5'1 .o22 t.477
.m3
.000 .009 .000 000
.m0 .000 .000 .000 .000
.395 .187 .268 .36 | .480 .290 t.344
3.276 2.252 2.O19 1.776 4.264 3.233
2.433 t.t82 1.125 t.3'17 |.467 |.284
.0m
.000 .000 t.000
,0m
r.000
Total Cost
r.058
r.833
Truck Traffic Accidents Propcrty damage Treatmenl of injuries L o s s o f u s e o f v c h i c l e. . . . . . . value of time lost Legalandcourtcos......... ts Damge amrds in excs of knom cms -.
r.000 t . q 2 r.000 2.430 r.0@ 1.000 t.000 5.096 r.000 r.000 r.000 1.000
1.000 1.880
3.660 3.561 2.146 t.0@ |.000 3.626
z.J)o
2.2t2 2.0't2 4.336 r.000 t.000
2.166
.000 .000 .000 .000 .000 .000 | .000
.06| .000 .000 .000 .0il .000
5.43 I 8.671 3.457 6.086 t.000 5.144
3.t07 t.000 4.630 t.192 t.065
Totalcost.....
r.000
2.254
| .023
Prenger CarandTruckTrafficAccidenrs
Properry damage Treatmenr of injuries L o s s o f u s e o f v e h i c l e. . . . . .... Value of time lost Legal and court costs . . , Damage aurds in exm of knom mrs
t.000 1.000 r.000 t.000 .000 .000
.r 9 l .059 .m0 .246 .0@ .0@
3 . 8 2 8 2.t3'l
1.053
3.833 1.9?5 3.670 |.240 30.344 . 1 4 5 8 . 5 r 6 .021
.000 .000 .000 .000 .000 .000
.38 r
.l8l . 2l 0 .349 .468 .283
3.344 3.723 2.n9 t.842 4.221
2.45'1 t.t76 2.384 1 . 3 |7 | .456 1.275
1.000 l . l r 3 3.9t7 1 . 5 4 1 r.000 | .134 3.322 1 . 8 4 8 l o o | : he .r F t l , - c :-u -s Ny t e : e T | n e s ,tr a t e . -a w. r ^ . .q ^ ^ i r e - t h e r e p o r t i n g o f a | | f a t a | a n d n o n f a t a I ' " f f i and nonraral. injurv accidentsand properry damase accidenrs or r l0o or morc "",;. ;r;:;":::::::::::"::-'.li' only
-
Total Cost
u."id"nt.'oi',lo'o. "o*. soarce..Ref.prus ,o," rs-zs suppre?J"ffi::T';":jT:::Ij;.rJr,jfl".::"g" onrv
worker would increase somewhat with age and with increased income, especially all work abovethe labor for and craft levelof income. The Wilbur Smith study used a discount rate of 4 percent per year. A higher rate' say 6 percent, would have lowered the total present worth considerably from the $ I 1,639,g41 reported. In the Illinois accident costs the nonreported accidents are included. The nonreportedaccidentsare primar'y property damageonly accidents of low cost per accident, usually less than $ r00. The Illinois publisied report tl5-251 does not give the number of and cost of the nonreported traffic
4()0
Traffic
Accidents
Traffic
Accidents
accidents,but the costs were obtained from original work sheetsand used in developingTable l5-9A. on a total basis the ratio of total cost to reported for and 1.848 urban accidents. The ratio cost is 1.541for rural traffic accidents car for property damage only accidentsis 3.233 and 3.972 for the passenger respectively. This ratio will vary state to state, urban and rural accide_nts, depending upon what the law states as the minimum cost of an accident which is not required to be officially reported. A detailed examination of Table 15-94 indicates those tralfic cost elementswhich are most often not wholly included in the official reports,such as value of time lost and legal and court costs. In the lllinois study and other similar ones, the accident data are obtained from the vehicle owners who' were selected from a statistically controlledsampledrawn from the statevehicleregistrationfiles. In the washington metropolitanarea study there were 96,100offficially reported traffic accidentshaving an averagecost per involvementof $527. There were 1.86involvementsnot officially reported for one officially reported involvement. The involvementsnot reported cost an averageof $ 95 each. comparedto $ 16'570'000 The cost of the reported accidentswas $ 50,661,000 for the unreported accidents. The total accident cost is therefore 1.33 times the cost of the reported accidents. On a vehicle-mile basis the costs were which 0.75 cent for reported accidentsand 0.24 cent for unreported accidents, is equivalent to 14 reported involvements and 26 unreported involvements per million vehicle-miles.
GENERAL GUIDES The large number of factors the environmentwhich affect thc complex of variable situations costsfor any one particular come by. When dealing with an lrc made to get its specificacci
The amount of accident red
to an existingfacility is more types of accidentsthan to any is Past number of accidents not rcducing the number and severity guide to an estimateof how Oe improvement. S e eR e f . l 5 - 1 . l 5 - 1 2 , n d t l d a ratesasrelated highway to design ei SOME SPECIFIC FACTORS
i
ACCIDENT
RATES
FOR ECONOMY
STUDIES
(l)The on For economystudies,three statistics traflic accidentsare needed: of to vehicle-miles accident rate, that is, the frequency of accidentsrelated given time period, (2) the driving or to number of vehiclesusing the facility in a and (3) the highwaydesignand traffic factorsinvolved. costper accident, the traffic accidentsneed to be convertedto dollars For highway analyses per day, per year, or other time unit so that the accidentcostcan be addedto the in motor vehicle running cost. Traffic accident costsmay be expressed cents dollars per highway mile, or other suitable dollars per accident, per vehicle-mile, unit. The most commonly used unit for measuringtraffic accidentsis l0 usually in terms of one million vehicle-miles, million vehiclevehicle-miles, highwayimprovementalternatives miles, or 100 million vehicle-miles. For the being considered,the accident costs may be estimatedfor each alternativein reduction from the base alternative,often the existdollars, or as a percqntage ing facility. The following pages present a variety of information to use as guide material in estimatingthe accident rates (and costs) when other more informationis not available. directly applicable
The main highway lu.too t{ curves.vertical grades,intersedioi tnd pavement surface condition. i cxist in combination the accident I grch combinationof factorsthe aod I segmentof highway which is e Accidentsand their location of motor vehicledriversand omplex are the factors &cision, the higherthe hcilitv are aDt to hars
lroublesome to tbc
Fcess. The
at
Traffic
Accidents
401
GENERAL GUIDES The large number of factorswithin the highway,the vehicle, the driver, and the environmentwhich affect the accidentrate and the accident cost form sucha complex of variable situations that good, solid, reliable accident rates and costsfor any one particular sectionofhighway or a specific facility aredifficult to come by. when dealing with an existing facility, however, every effort should be made to get its specificaccidenthistory rather than to usegeneralestimates. The amount of accident reduction that can be expected from an improvement to an existingfacility is more dependent upon the rate of past accidents and the types of accidentsthan to any other singlefactor. Knowing the facts about the past number of accidents not only a good guide is to selecting bestmeans the of reducingthe number and severityof accidents, but it is also the best available guideto an estimate how much reduction of in accident cost may be expected by theimprovement. See Ref. l5-r, r5-r2, and r5-2i for discussions summaries and of accident ratesasrelatedto highwaydesignand traffic operations. SOME SPECIFIC FACTORS The main highway factors that contributeto traffic accidents are horizontal curves' vertical grades,intersections, access points, structures,roadside objects, and pavement surface condition. when these elements are unfavorabreand existin combination the accident rate goesup in somegeometric ratio. under suchcombination factorsthe accident of ratemay be 6, 10,or 20 timesthe rateon a segmentof highway which is a level tangent without structuresand access. Accidentsand their location are in someform of ratio to the decision process of motor vehicle drivers and pedestrians when within a trafficway. The more complex are the factors bearingsimultaneously upon a driver or pedestrian decision, higherthe accident the rate. consequently improvements a highway to facility are apt to have high accidentrate reJuction when one or more factors troublesome the driver's decisioncan be removed to to simplifythe decision process. The decisionprocess composed the followingsteps: is of (r) recognizing the hazard at hand or forthcominc, formulating arternativeactions to avoid an e) accident,(3) deciding upon the most favorable arternative through a process of evaluatingthe merits and demeritsof each,and (4) taking the act]onselected as beingthe betterone. when it is rearized that between step(l), recognition, and step(4)' action,theremay be only a fractionof a second of time or l0 to 20 ft of distancein which to avoid the hazard,it is readily realizedthat the decision process a heavytax upon mostminds. Accidents is arecaused areavoided or by fractionsof an inch in distance and hundredths a secondin time. providof ing the type of highwayand the type of traffic behavior that keepthe decision processes simpleis onegood approach accident to reduction.
&2
Traffic
Accidents
Traffic
Accidents
The speeddifferential betweenvehiclesis a strong factor in producinghigh accidentrates il5-431. This factor is probably one reasonwhy two-lane highways have a decreasing accidentrate above ADT's of 7,000while below 7,000 ADT the accidentrate increases with increases ADT. in Intersections hazardous. Intersectionaccidentratesare highly sensitive are to the traffic flow on the l,ninor legs, but not so sensitiveto increasein traffic flow on the major facility. Elimination of intersections is the factor that contributes heavily to the low accident rate on fully controlled access highways. Reduction in the number and amount of vehicle speed changesis also an important factor which contributes to the low accidentrateson freeways. The factors of speed changes, intersections, and accesspoints probably account for the accident rates on four-lane highways without mediansbeing as high or higher than the rates on two-lane highways. Roadsidedevelopment, higher total traffic volume, and the resulting complex decision processes contribute heavily to the high accident rate on four-lane facilities without medians. GUIDES TO ACCIDENT MTES ON SPECIFIC TYPES OF HIGHWAY ELEMENTS for In analyses the economy of highway improvements,often, particularly in project formulation, the alternativesdiffer only in such elementsas horizontal curves, vertical grades, intersections, and traffic controls. To make a proper comparison of such differences the accident rate resulting from such specihc elements needs be known. to Horizontal Curvesand Vertical Grades
is not much more than u g"n""atii figure 19.27. I The hazardouscharacterof I frcl sight distance,superelevation, design standards. An occasional I a series of curves. AccidentsC improved signing, increasingsigl improvingsuperelevation. r Vertical grades contribute to"l Even I and 2 percentplus gradcri increasevehicle speeddownhill { distance. Run away truck accid{ Restrictedsight distanceon grafl contributes greatly to accidents{ more frequent(more per mile of hl Illumination
Many factors are involved in I illumination. Lighting doesredud applied to locations known to lra lighting on a selected basisis as d to amount of light is preferable hil for ation is desirable effectiveaccil a favorablefactor. Generalratcs{ lightingare yet to be developed. Intersections
The review of the literature on accident rates on horizontal curves and verticalgradesas given by the AutomotiveSafetyFoundation l5-1, pp.33-371 I with anlgease in either is positivein its findingsthat the accidentratesincrease or both of thesefactorsof alignment. The severalwriters are not in agreement as to the amount of increaseand their specific rates may not be attachedto specific degrees of curves or percent grades. The Cornell Aeronautical Laboratory concludes that curvesflatter than 4 degrees lesssteepthan4 percent or is have no materialeffect on traffic accidentrates ll5-121. This conclusion based on an analysisof accident reports for Contrecticut,Florida, and Ohio. For economy analysesit seems preferable to give the weight to earlier as reports. Table | 5-l8 is thereforepresented a guideto makingsomeallowance for increasedtraffic accident costs with increasein horizontal curvature and vertical grades. Although Table l5-18 gives the appearanceof authority, considerablejudgment was exercised in using the evidenceavailable: For instance,the statement"Sections with curves over 5 degreesand gradesover sectionof highway" 5 percent had 19.27times as many accidentsas the average
Accident ratesat that they are not detailed S ll5-1, pp. 47-591, yrct others offer good guidcr rates at intersections One-wavStrC Conr i n ga h i g h
Traffic
Accidents
@3
is not much more than a generalized conclusiondespitethe preciseness the of figwe 19.27. The hazardouscharacter of horizontal curves comes from the factors ol sight distance,superelevation, frequency of curves, and adherence uniform to designstandards. An occasionalcurve is more productive of accidents than is a series of curves. Accidents on curves have been materially reduced by improved signing,increasing sight distance,reducing tendencyto skid, and improving superelevation. Vertical grades contribute to accidentsprimarily at their crestsand sags. Even I and 2 percentplus grades slow down heavytrucks. All grades tend to increase vehiclespeeddownhill and, therefore, considerably increase stopping distance. Run away truck accidents not uncommonon long steepgrades. are Restrictedsight distanceon grades,whether at crestsor at horizontal curves, contributes greatly to accidents grades. But as these restrictions on become more frequent(more per mile of highway)the accidentrate decreases. Illumination Many factorsare involvedin the relationof traffic accidents and highway illumination. Lightingdoesreduce nightaccidents the whole,especially on when appliedto locationsknown to have a high rate of night accidents. Installing lighting on a selected basisis as effective on a continuous as basis. A uniform amountof light is preferable high and low spots. A minimumlevelof illuminto ation is desirable effective for accident control. A reflective pavement surface is a favorable factor. General rates ofaccident reduction effected throughhighway lightingareyet to be developed. Intersections Accidentratesat intersections dependent are upon sucha complex offactors that they are not detailed here. The AutomotiveSafetyFoundation publication , , l l 5 - 1 , p p . 4 7 - 5 9 1 S y r e k I l 5 - 4 5 A ] , W e n g e r t l 5 - 5 3 1 ,S o l o m o n I l 5 - a - 4 1 a n d othersoffer good guidesas to probableaccidentratesand changes accident in rates at intersections under a variety of designfactors and traffic volumes. One-wayStreets Conversion one-way to streets will reduceaccidents to 45 percent 20 including a highreduction pedestrian in accidents tl5-1,p.141. Speed Speed of traffic per se is not a factor that contributesheavily to accident rates. on the other hand the differences betweenspeeds vehiclesin a traffic of stream do contributeheavily to the accidentrate t15-39and 15-431. Speed, though, does contributeheavilyto the severityof personal injury accidents, in
4O4
Traffic
Accidents
Traffic
Accidents
Rural and in cost of property damage' number and extent of involvement' and freeway and toll per accident than urban accidents accidents are more costlf on other highways rnot" costly per accident than accidents highway accidents ut" lower' where the traffic speed is much relating traffic of figo.", and tables in this chapter There is un o.irrio' of speed is accounted for thought that the factor speed to accident rate' It 'is highway, and character volume, geometric design of the in such factors as traffic types of examination' However' for similar of the specific facilities under a higher amount for the should be taken at accidents, the cost per accident the higher driving speed' ult".nutiu" or facility which has cost of proposed higlway improvements,.the In the economic analysesof estimated acceptably being considered usually can be accidents on the alternatives speeds' without directly considering specific AND COST RELATED TABLES OF ACCIDENT RATES TO DESIGN AND TMFFIC FACTORS as guide tables and curves to be used There are presented in this section informationinestimatingtherateofaccidentsortherateofaccidentcostof
TABLE I5-IO DtnEcr Cosr oP TnnPntc AccIDENTS orTnnvEL P E Rl 0 M I L L I o N V r u t c l s - M t l e s an Index of l'25) C o s t U p d a t e d t o 1 9 6 6U s i n g ( B a s e d o n 1 9 5 8A c c i d e n t s l Illinois Registered P a s s e n g eC a r s r Rural F e d e r a l - a i dP r i m a r Y a n d s t a t eh i g h w a Y s I ' e d e r a l - a i ds e c o n d a r Y : StatehighwaYs.'." Local roads Subtotal N onfederal-aid: StatehighwaYs....' Local roads Subtotal All roads and streets: StatehighwaYs...' L o c a lr o a d s . ' . . . ' . Total ..
x
proposedhighway facilities o, for i is unavailable. Despitethe large i scarcity of published accident ratn{ and facilitiesin the detail d designs are reported by highway system' { application. A few reports,howd to for the material follow. For comparisonsof the cffcct I severity of accidents, urban, d
Urban Full access 2,068,597 cont.ol Partialaccess control 883.328 | N o c o n t r o .l . . . . . . 2,963,77 Suburban 198,746 Full access control Partialaccess control I,045,904 N o c o n t r o .l . . . . . . 2 ,r 3 0 , 1 5 1 Rural Full acccss control Partialaccess control N o c o n t r o .l . . . . .
Area and Degree of Access Control
|I d rl
l l
tllinoisRegistered Trucks,All TYPes
't,054,287 3,595,160 s,562,289
l{ r l 4
HighwaYSYstem
MuniciPal
Total
R"tt+-l M u n i c i P a l
Total
Irr t r-.a rcd
lr4
s72,905 $ I 14,289 100,469 54,046 66.928
s 9 1 . 9 5 5s42,846 $52,660
45,699 28,962 35,424
Urban Full access control
I 1 5 , 6 6 1 104,280 22,019 I 51,426 4 0 , 7 1 35,660 67,969 73.632 t96,'769 36,125 1 4 1 , 8 9 9 35,686 4 t49,604 35.77 r08,060 4l ,458 l 3 3 , 7 8 2 37,069 L | I 20,928 40,170 95,798 46,670 53,470 61,466 46,088 5 2 , 8I 5
Partial accesscontrol Nocontrol .... ., Suburban Full accesscontrol Partial access control
63,146 252,624 96,319 t5t,264 89.065 163,626 7 3 , 7 1 8 t44,061 82,022 149,684 76.334 147,495
69,290 42,944 47,t69 4'7,821 42,375 45,601
Nocontrol ...... Rural Full accesscontrol Partial accesscontrol Nocontrol ...... Sozrce: U5- bc
cases) significant data (20 or fewer sample Sample was too small to provide Ref. l5-4. Soarcer
This tablc b streets.
Traffic
.Accidents
405
proposed highway facilities or for existing facilities when historical inlbrmation is unavailable. Despite the large volume of literature on the subject there is a scarcity of published accident rates and cost rates applying to specific highway designs and facilities in the detail desired for economy anaryses. often the data are reported by highway systems, as in Table r5-10, and as such has but timited application. A few reports, hbwever. are herpful and these reports form the basis for the material to follow. For comparisons of the effect of the degree ofaccess control on numbers and severity of accidents, urban, suburban, and rural, Table l5-ll is useful. T A B L E I 5 - II Tnnrprc AccroENTs ANDAccloeNr Rnres sy UnseN nno RuRAL AREAS DEGREE Aa"us Co^r*ol AND oF
Number of Traffic Accidents Area and Degree of Access Control Vehicle Miles (Add 000) Fatal I nj ury Nonfatal Injury Accident Rate per lm Million Vehicle_Mila
Property Damagc Only
Total
Fatal I nju ry
Nonfatal I njury
Property Damage Only
Total
Urban Full accesscontrol Partial access control Nocontrol ...... Suburban Full accesscontrol Partial access control Nocontrol ...... Rural Full access control Partial access control Nocontrol ... Area and Degree of Access Control Urban Full access control Partial accesscontrol Nocontrol ...... Suburban Full access control Partial accesscontrol Nocontrol ...... Rural Full accesscontrol Partial accesscontrol Nocontrol ....
2,068,597 883,328 2,963,77 |
l5 lr5
7 46 94
I,l0l 8?l 5,082
2 , 7t 6 3,478 10,384
1,852 4,385 t5,581
1.69 4.08 3.88
53.2 98.6 171.5
l3l 394 150
t86 496 526
t98,746 I,045,904 2,r30,15t 't,054,287 3,595, r60 5,562,289 Person Fatalitics
9'l 862 4,083
t69 2,644 6 ,t 6 4
273 10,341
3.52 4.40 4.41
48.8 82.4 191.7
85 253 289
t37 3.to 485
r98 172 394
4 stq 2,600 5.986 Persons Injurcd
5,908 4,804 12,070
10,635 7,5'16 | 8,450
2.81 4.78 7.08
64.2 107.6
84 134 2t7
t5l 2tl 332
Rate per I00 Mitlion Vehicle-Miles Fataliries
Rateper 100Accidents
Fatalities
I njuries
I njuries
4l 4l il9
1,8t0 1,430 8,074
| .98 4.64 4.O2
88 t62 212
1.06 0.93 o.76
47.O 32.6 5r.8
8 53 t09
180 |,405 7,208
4.03 5.07 5.12
9l t34 338
2.93 t.49 | .05
65.9 39.6 69.'1
I
231 220 484
8,836 4 , 9l 8 t0,875
3.2'l 6.12 8.70
l2s t37 196
2.17 2.90 2.62
t t
83. r 64.9 58.9
Joarce. U.S. Bureau of public Roads, l95g Data
This table is basedupon a wide geographical expenence main highwaysand on streets. The accident-reducing effect of access control is strikingly favorable.
Tta?Jic Accidents 40,6 specific urban routes' Table 15-12for For urban system studies or for C h i c a g o , I l l i n o i s , r e p o r t s b o t h a c c i d e n t r a t e s b y s e v ehighc l a s of $ 1'020'500 t c o s t s r i t y costs a n d a c c i d e n notice is the per 100million vehicle-miles' Of important Street signalizedsection of the Congress per 100 million vehicle-milesof the standard cost of only $ 160'200for the full Expresswayas cornpared to the expressway.
TABLE I5-I2
l9 58 Costs tl C utcnco' I LLlNots' A 'A-c ic t D u ,N TR A T E S N DA c c t o e N t ' ' Co E of 1 25) f r o m 1 9 5 8t o 1 9 6 6b y a F a c t o r Updated n N u m b e ro f A c c i d e n t is 1 9 5 8
Street or HighwaY
Traffic
Accidents
importantly related to the Prl shouldbe d theyaccrue soever
)
Accrol Tnrrpprc rNrue CulcncoAl (CostsUPdated
Travel Accident ltem
I
Accident Rateper
lostof Acper :idents
Tclricle-milesof travel' million Xumbcr of accidents
- ' ' 'i
PropertY
Fatal I nJury Nonfatal I nlury
Damage OnlY
Total
100Million | 100Mtllton Vehicle-. Vehicle| milcs Imiles'($1 1,424 1,327
6))
---.t F.ralaniury ..-i . injury t{onfaral fhogcrrldamaSonly-. - -... -{ T d . l . . - . .. . . . - . . . . . - - - - . rrcpcrl(Ddbw*b ..---------------
a Twelve rterials I t d T e ns e l e c t eP u r kD i s t r i e s l r e c t s I LakeShoreDrive I l. Limitedaccess(ramPs) | 2. Signalized I l 3 . P a r t i aa c c e s s ExPresswaY Congress ' l . F u l le x P r e s s w a ) n 2 . S i g n a l i z eid c e n t r a l di r businessst ict AccidentratePer 100million vehicle-miles l. On arterialsystem ' 2. On exPressways AveragecostPeraccident' 1 9 6 6d o l l a r s ,
48
to
4.648 | I 2,801 I 1 . 8 4 5 | 4,874
t'l,499" 6,735 ) nr5 992 47'7 508 ll5
775,200 729,100 3I 2,200 551 ,000 39I ,000 l 60,200 1.020,500
I
-------------lF AEr*
5 2 0 0 0
449 221
1 1,57 '769 402 346 87
/)
162 28
I,102 919 2'79 2.018
'
I 3.9 0.00 7,250
378 89 r,200
1,042 190 281
I A)4
279 540
|,424 219
* Of this total J6 percent were dt intersectlons factor per accident wcrc used as a converston I ransportation Study 1 89 involvemenis ,\oter In lhe Chicago Areu Soarcer Ref l5-23.PP 35l-353'
countis Cook and DuPage but covers Table l5-13 is similarto Table l5-12' rates would not b accident costs and of the Chicago area' These traffic rates arc figures in Table 15-12' but the exDectedto agree witt' it'e Chicago ofih" ,um. generalorder of magnitude' 15-14on accidentrates as aflectedby The North Cutofi"ul"po'i in fuUft factthat.:^"-it":::li1l5l1 " orr[Br *t ont important c.ntrol brings accesscontrol access on rate of accidentsJl[ thC I number of accidentsanc in the tie high reduction in the parallel tlpt":t:uv, conventional arterial t;;;;-;;t; :":":T:::"::"t"tiT: T h u s t h e r e i s a d o u b l e g u i n , f i . , , t o t h e t r a f f i c t h a t s h i f t e d t o t h e n eThis p r e sis w a J w e x fact remained on the older facilitv' and second, to the t'uffit thut
Traffic
Accidents
4O7
or sts
importantly related to the principle of analysis that all consequencesto whomsoever they accrue should be considered.
TABLE I5-I3 R T u p r r c A c c T D E N T l r e s . { l . . r oC o s t s s v H I c H w e v T v p E r Nr H E C H r c n c o A n e , r ( C o o r a N o D u P . c c E C o u N r t e s ) , 1 9 5 8 ( C o s t s U p d a t e d f r o m 1 9 5 8t o 1 9 6 6 b y a F a c t o r o f 1 . 2 5 )
Local Streets
m
3et lrd
Travel Accident Item
Arterial Streets I0,575 332 48,069 208,07 I 256,472
Expressways
Total
V e h i c l e - m i l e s t r a r e l ,m i l l i o n of
2,1 0 0 146 23,77 | t90,443 2t4,360
t,027 t2 939 4,29l'
\ )4)
13,702 490 72,779 402,805 476,074
;
lxr Lion
citl
Numberof accidents F a t u li n j u r y Nonlatainjury .. l Property only damage Total . . Accidentrateper 100million vehicle-miles F a t a li n j u r y N o n f a t ai ln j u r l . . o Property amage nly d Toral ..
n m m m m m m
6.95 |,t32 9,069 10,208
3.t4 455 |,967
1 / t<
l.t'l 9l 418 510
3.58 531 2,940 I 475
Cost of accidentsper 100 million vehicle-miles s20,700 F a t a li n j u r l $47,000 l,648,400 836,200 N o n f a t ailn j u r y . . 2 , 1 7 1 , 8 0 0 482,700 Propertydumage only 3,867,200 l,339,600 Total ..
Soarce. Ref. l5-28,
$ I 2,200 r81,600 r91,000 384.800
r 24,1 0 0 9 r 1,600 7 l 9,700 1,655,400
TABLE I5.14 Tupptc AccTDENT R,treson NonrH C,rnol-lNa. Hlcuwlvs AND ExpnesswAys Pln,rllel CoNVENTtoNAL AccEss-CoNTRoLLEo
Conventional Highway
factor.
Item
Before Opened
After Opened 48.6 65 83 169 r28 260
E x p r e s s w a y Expressway
New (1961) Expressway
nties )t be s are :d by Note n the raffic. sway, act is
M i l e so f h i g h w a y. . . . . . . . . V e h i c l e - m i l e o f t r a v e l ,t i l l ; " ; s Reported number of accidents I n j u r ya c c i d e n t s . . . . . Total accidents R a t e p e r 1 0 0m i l l i o n v e h i c l e - m i l e s I n j u r ya c c i d e n t s . . . . . Totul accidents
Soarcer Ref. l5-10.
.......
48.6 104 158 343 t52 330
44.3 '72 24
A A
33 6l
4()4
Traffic
Accidents
Traffic
Accidents
of highways from the In Table I 5-l5 is the California experiencewith six types This table has added value ordinary two-lane highway to the full freeway' accidents,the latter by type it becarrse reports the single vehicle and multivehicle ofaccidentandwhetheratanintersection.Notethehighrateof0.68accident highways and the per 100 million vehicle-miles at intersections on the two-way rate of only 0.045on the freewaYs. Theaccidentratesforthreeclassesoftrucksonmainruralhighwaysare giveninTable15-16,byseverityclasses.Truckshaveatrafficaccidentratemore favorablethanpassengercars'andthetruckcombinationhasthebetterrate within the truck class. Tablel5-lTfromtheworkofRoyJorgensenandAssociates[15-27]ismost helpfulforestimatingprobableaccidentreductionsfortheso.called*spot Note the footnote that gives imirovements. and traffic control improvements. In the useof this table, judgment some guide to the reliability of the percentages. withr-especttoeach,p""ifi"applicationisadesirablefactor.Areadingofthe full report is recommended. practical form a guide to the Table 15-18 is an attempt to reduce to a grades on traffic accident rates' The effect of horizontal ",r*", ond vertical accidentswith an increasein literature more often indicates a positive increasein it does that there is no effect. Butparticularly the amount of each factor than there is a noticeable increasein accident ratewhencurveandgradearecombined will haveto await more at the samelocation. Accident ratesof provedreliability ofdesign' on thorough observation thesetwo factors Figuresl5-land|5.2willbefoundmostusefu|instudiesofmedianopenintensivestudy ing anJ widening of bridge roadways. Mediansare undergoing -b-e3f{esign features' evidence as to their in an effort to reach more positive practiceand with Fig' l5-2' the economyof in Bridge widening is well accepted with greatercertaintythan before' suchwideningmay be examined CORNELL AER(,NAUTICAL LAB('RATORY STUDY
80
P
9
_E eo
g
=
E 4 0
o
!
!P
o
!E
AsapartoftheNationalCooperativeHighwayResearchProgram,administeredbytheHighwayResearchBoardoftheNationalAcademyofSciences,the a study to determine cornell AeronauticalLaboratory, Buffalo, N.Y., undertook and highway design the relationship of motor vehicle accidentsto highway types from their reports elements. Some of their results are presentedhere as obtained a t l 5 - 1 2a n d l 5 - 4 7 , n d l 5 - 2 8 4 1 ' ANALYS$ OF THE ACCIDENT DATA FromthestaterecordsforConnecticuttlg62,lg63,and1964],Florida (the only stateshavingthe [9 months of 1963, 1964], and ohio 11963,19641 completerecordsandful|detailsnecessarytothestudy)theaccidentdatafor
P
i_8
.s
.E
s
9
60
.s
9
40 I
Number of
'medion-openings" per closeo mile
8
9
The percentage reduction in traffic
accidenlsto be expectedfrom the closing ofopenings i n m e d i a n st 5 _ 2 7p . t 5 t l . , I
P
d
.9
O = Initiqt. bridge wrdth mtnus Inttiol roodwov w i d t h ,b o t hi n f t
Distonce bridge sidened. ft The percentage reduction in
widening r,".ni:"fi.'ft::.,[ orthe
;: ,":t"ii."
asa resurt the or
410
c ) @
$
Traffic
Accidents
Acdderrc
+
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6 6
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Traffic
Accidents
411
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9 -
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m @ 9 o)o)1s.1 d d $ s 6 s
+
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a F
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412
Traffic TABLE I5-I7 PEnceNrecg ExpEcrnoREDUcrloNs rNTnepprcAccroenrs ErpectEo ny IvpnovelreNton Fecrlrry
Accidents
Traffic
Accidents
r^t
Type of lmprovement
Accident Reduction, Percent
Utr Rlra
Type of Improvement
Urban Number ot of Rural Lanes
AI
Fatal lnjury
Property Damagc Only \ccidentl Comments lnstall minor leg stop control Install all-way stop signs Install warning signals .. . . . . . . . ..
I
Route sections Eliminate parking Install/improveedgemarking .... InstalUimprovcwarningsigns .... Install/improvewarningsigns . .. . lnstall/improvewarningsigns .... Install/improvewarningsigns .... lnstall median barrieN .
U
R
Install warning signals
| l
U
I I
t l
|
' 2 2 plus
2 plus r
32 t4 t4 20a, 36 l8a t2 42 t2 44 38 38 38 5 90 l0 15b
3 l'1^ l4^ 76a 32a 2
See Ref., p. I7O
lnstall warning signals
U U l r f:j U U U
Add pedestriaq signals Add pedestrian signals lmprovesignals .... Improvesignals.... lmprovesignals ....
R R
t '
I I
t I I |
| 2 olus
^ . z Dtus 2 plus
u
l !
A d d p a i n t e d / r a i s e d m e d i a n. . . . P a v e m c n t r e s u r f a c i .n. g . . . . . . . . P a v e m e n t r e s u r f a c i .n. g . . . . . . . . P a v e m e nrte s u r f a c i n . . . . . . . . . . g Shouldcr stabilization - . . . . . . . . . Widen shoulder, no dimensions . Widen traveled way, no dimensions Widen travcled way from 9-ft lanes Widen travelcd way from lO-ft lanes Livcstock fencing Modernization to design standards Modernization to design slandards .
U U
R
46 2l 59 46 7a 3o,// l6 -65b -6a 22a
See Ref., p. 182. Depends on number ol' wct pavement accidents and iotal number per mrleBased on accident criteria. See Ref., p. 186 Improve signals Curtailturningmovement .... Add left turn lane w/o signal . ' .
1
l
R R R R R R R R R
I 2 plus
)
2 2 2 2 2 or more 2 2 plus
r
u,
U, U,
I
Add left turn lane wo signal . ' . Add left tu.n lane wo signal , . .
u:
-37a
Livestock accidents only
Add left turn lane w/o signal . . . . . Add left turn lane w/o signal . . . - Add left turn lane w/o signal . . . - ' See Ref., p. 82. Addleftturn lane& signal ..... Add leftturn lane & signal -
u,
u
li
-40b
... -. -
Grades Add climbing lane C e n t e r l i n c s t r i p i n g a tr e s t s . , . . . . c Horizontal curves
R R
2 2 2 2 plus 2 2 plus 2 2 plus 2
0 64
0
0
Limited data.
Add left turn lane& signal . . . Add left turn lanc& signal . . . . wo tun lG Add left turn signal w/o tum le Add left turn signal
Install delinearors lnstall delineato6 lnstalUimprovewarningsigns .... lnstalUimprovewarningsigns .... Reconstruct curye Install warning signs and delineators Install warning signs and delineaton Bridge/underpass Install delineato6 Install delineators Intersections Stop ahead sign Installyieldsign.... Install yield sign lnslall minor leg slop control Install minor leg stop control .. . . . . . . . .
R R R R R
2b 46a 5'l 52 88
l6 -t0b 7l q 89 -2'la 4la
See Ref., p. 48. Effective
Add left turn lane, signal & illrInstall new traffic signals . . . -.
6l 23a 96
for night accidents.
U R
m 22"
4't 5la
Deslicking Rumblestrips
tThe symboB No symbol
R R
2 2 plus 2 2 2 plus
_8b 62 89 t
R
47 59a -4
96 80 7l l8a
Low ADT where rolling stop is saf. When angle-type
U U U U
,
)
48 38a
2 plus I
2)
accidents are 5O7 or more
Traffic
Accidents
TABLE 15-17 (continuefi
Accident Reduction, Percent
413
Type of Improvement
Urban Number or of All Rural Lanes Accidentr
Property Fatal Damage Injury Only \ccidentl 89 67a 'l3a 29^
Comments
Install minor leg stop control Install all-way stop signs . . Install warning signals Install warning signals Install wa.ning signals . . . . . . . ..
R II
2 2 2 plus 2 2 plus
65 68a -27 b 56a 2tb l3 3a -z 42^
See footnotet.
U R
R
See Ref., p. 52.
Add pdestriaq signals Add pedestrian signals Improvesignals.... Improvesignals.... Improvesignals....
U U U
I I
2 2 plus 2 2 plus 2 plus
56a 42a 35a l0b 45b
Changes to improve drivcr's response to signal-vision, attention, etcetera,
R
lmprove signals Curtail turning movement Add left turn lane wo signal Add lcft turn lane w/o signal Add left turn lane Wo signal
I I I I r I
2 plus 2 plus 2 2 plus 2 plus 4 40 l9a 6
57 39 80a 54a -t6
T-intcrsection.
U R
U U R U R R R U
I I
Add left turn lane u/o signal . . . . . . Add left turn lane w/o signal . . . . . Add left turn lane w/o signal . . , . . . A d d l e f i r u r nl a n e & s i g n a l . . . . . . . A d d i e f t t u r nl a n e & s i g n a l . . . . . . A d d l e f t t u r n l a n e & s i g n a .l . . . . . . A d d l e f t t u r na n e & s i g n a l. . . . . . . l Add lcft turn signal wo turn lane Add left turn signal w/o turn lane Add left turn lane. signal & illumination l n s t a l n e w r r a f f i c s i g n a l s. . . . . . . l . . .
2 2 plus 2 2 plus 2 plus 2 2 plus 2 2 plus 2 plus
79 5la 33 27 43a 62 5 I 58a
T-intersection. T-intersection. Y-intersection.
42a 39 46 29
-28b
51 76 50
Proven hazardous intersections, 60% right anglc and left turn
rI
U & R 2 plus
Deslicking Rumble strips
U R
z prus I 2 l
I I
accidents.
20 2'tb
l5 26b 24b
*The symbols in the percentage reduction columns have the following meaning: No symbol Good estimate O-3OC,, a b Rough estimate Very rough estimate
30.'to'7a
1O_l5O%
No estimate made ovet l5O 7a The percentage range to the right means that there is at lcast a jS y. certainty that the true average percenrage reduction is within the percentage given in the column, plus or minus the range given above. For exampre, theentry 68a means that the range of 75 percent probability lies between a reduction of 9g to 3g % and a reductron of l0o % ( 1 3 8 % ) t o a n i n c r e a s eo f 2 % . t Minorstreetmustbe35%ormoreoftotalintersectionvolume,whichislessthang.00OADTSource : Ref . l 5-2'1, pp. 146-t49.
414
Traffic
Accidents
Traffic
Accidents
rural highways were obtained in full detail and associatedwith the specific roadway location by 0.1-mile segmentsand traffic volume. By statisticalprocedure the following equation was developed as one which closely fits the three-state experience:
lil
ve,r-uEs C-Coed on S,cN4pt-E CaC TorAL AcclDENrsoN Ohio ApproximateADT 490
log"T: a + brlog"T+ brlog"zT
Where ,Z:
(rs-r)
Geometry*
1650 0.37
q
Lbr,b, T_me&oaveragedailytrafficvolumeontheroutesegmentsas grouPedfor analYsis In preliminary trials the equation l o g " A : a + b t l o g eL + b r l o g r T
ffie&fl number of accidents in the 0.3-mite length of route as segments grouPed for analYsis : constants valuatedrom the data f e
Baselinef
0.13
r.x
0000 0G00 c000 00I0 000s cG00 OGIO OGOS c0I0 c00s 00ls
CGIO CGOS OGIS COIS CGIS
1.00 .40 .60 .70 .58
t.74 2.12 | .'17 2.0'l 2.48
1.00 l q
1.36 LE7 2.88 1.43
z{
td
IJ t7 rl
t.{
( r5-2)
was used where L is the length of route segment,but the variable length was found to have an adverseeffect on the results. The final choice was to hold the y!*ent length constant and to let the ADT be the singlevariable factor' The factors of highway design that had the greatestinfluence on the number TABLE I5-I8 Gn.qoes R,rresl-onHottzoNtnLCutveseuo VEnrtc,qL AcctDENT ( B a s e o n R e f s l 5 - 1 , p . 3 3 - 3 7 5 - 6 , n dl 5 - 4 0 ) d p l, a .
Ratio of Accident Rate to Degreeof Curve or Percent Grade Rate on Level Tangents
2.2r
2.W 3.42 t.72 3.89 2.fi 2.74
u
II
u
3.05 4.41 3.04 3 .l t 2 . 6 r 3.30 2.73 3.04
4.t7
u
3l LI
3.65
2i
Remarks
Horizontal Curves
Vertical Grades 1.0 t.l 1.5 2.0 2.7 4.9 6.2 7.6
t-z
* Key
C = G = Curvature prescol Gradient prsent lntersections Ptwnt {
I
0
I 2 3 4 5
o
1.0
l-J
For a combined horizontal curve and vertical grade use the sum of the two ratios for their respective Example, lor a 4-deg curve and a 3 percent. grade the ratio of values. a c c i d e n t st o t h e l e v e l tangent accidents would be 2.4 plus 2.0. or 4.4. This table is not basedon highly reliable experience.
I
I
E.xon1l,'. CGIO . ( urred and gndcd rcfl * Baseline : Number of accidcns per 14f, Soar.ei Ref. | 5-49.
,|
8
o
l0 1l t2
I J
14
ll
1.6 2.O 2.4 2.9 3.6 4.3 5.2 6.3 7.6 9.t 10.8 t2.5 t4.4 16.3
rl of accidentswithin a segmentsi (2) control, and medians)' horizo{ or no. (4) intersectionryesor no' curves, grades, intersectionsand oot present within the 0-!*
cur!'cs showing ho$ rhc
10.8 12.4 l4.l
Grch of many highnX Curves on
{dct curverurc
crrv'cs (x
Tfb frfl
Traffic
Accidents
TABLE I5-I9 SeuplEVeluesop C-Coepr,rcreNrs, ReLnrrve on AccTDENT RATEs: Torel AccroeNrsoN CouveNrroNal Two_LeNe Runnl Roeos
415
Geometryx
Ohio ApproximateADT 490 | 650
Florida Approximate ADT
Connecticut Approximate ADT
5000
I.JZ
490 0 .l 0
1650
5800 0.95
490 0.05 l.00 1.52 1.40 2.tl 3.1 l 2.12
t-st
| 650 0 .l 5
5800
0.59
Baselinel
0 . 1 3 0.37 r.00 .40 .60 .70 .58
t.74 2.12 1.77 2.O7 2.48 2.21
0.28
0000 0G00 ct000 00r0 000s
cG00 OGIO OGOS
1.00
1.36 1.87 2.88 t.43
1.00
1.06 1.40 2.58 1.24
1.00
1.95 1.59 1.49
r.00 r . 0 0
1.32 t . s z 1.98 t .7l L55 t.64
1.00 1 . 0 0
1.06 1 . l l 0.78 0 . 8 5 2.30 2 . t 9 0.96 1 . 8 6
c0r0 c00s
OOIS CGIO CGOS OGIS COIS CGIS
Key: C = G =
2.O9 3.42 t;72 3.89 2.56 2.74
4.41 3.18 3.30 3.04
r.36 3.28
1.22
) 6,') ) l <
0.9 r
1.58 1.04 2.29 0.93 2.89
z.lo
2.t6
z.Jo
t.62 2.22
J.5Z
1a1 1 a l
2.88
l 9l t.69 2.39
1.09 2.62
5.tl
2.00 t.'72 2.29
L-O I
0.93 2.20 2.09 t.92 t.l5 3.30
3.05 3.04 2.61 2.73
4.17
2.15 2.74
J. /6
3.80 2.28
7.52 6.55
2.28 1 . 2 4 4.02 r.98 r.95 J. /O 2.23
z. tJ
1 ^ a
3 . 6 5 2.76
S : 0 = Structures present
Curvaturc present Cradient presenl
Geometric feature not prcsenl
I : Intersections present Exanplc: CGIO - Curved and graded segment with intersection(s), but no structures. 'l B a s e l i n e= N u m b e r o l . a c c r o e n r sp e r y e a r p e r 0 . 3 - m i l e segmenl Sdr/cc. Rcf. l5-49.
of accidents within a segment were (l) highway type (number of ranes, access control, and medians),(2) horizontal curvature-yes or no, (3) verticargrades-yes or no' (4) intersections-yes no, and (5) structures-yes or or no. The elementsof curves' grades, intersectionsand structures were identified simply as present or not present within the 0.3-mile segment. In the main results, this siudy gives curves showing how the accident rates per 0.3-mire segment vary with ADT for each of many highway types and designelements. curves on grades were found to have no marked effect on accidentsbelow {-deg curvature and 4 percent grades, so the segmentswere identified as having curves or grades onry when they were 4 deg or sharpe and 4 percent or steeper. r This finding is questionable as based upon references ln the literature ll5-l and
416
Traffic
Accidents
Traffic
Accidents
15-61 and as concruded the cornell report in the in review ofriteraturet15-12, p' 221' Perhaps the states of connecticut, Florida, and ohio did not offer sufficient observationwith respectto curves and gradesto bring out their effect upon accidentrates. ACCIDENT RATES The original Cornell publication ll5-l2l is recommendedas a source of accidentratesfor the severalbasictypesofhighways and the four designerements and for the severityof accidents. onry a feiv ilrustrativesetsof curvesand one table are given here of over 200 pagesof dutu and curvesavailabre the original in publication. Figure l5-3 givesfor ohio the annuarnumber of accidents basichighway by
type. Figure l5-4 givesthe cornli common types of highways. In I increases the numbersof acc{ in accident rates to vehicle-miles {
b
5 4
c
1 z
E o g E
I
o
d
c
o
.9 o. o o E
5 4
1
lo0 .80 .60 .50 {0 .30
c o E o a
a )
: .80 E
dl
o
o d c o
.60
o8 o6 .05 o4
n1
.02
I
o E t E c
o8
.04
2 2 4 4 Lones, medion, occess no no control Lones, medion, no portioloccess conlrol Longs, medion, occess no no control Fic. l5-4. Averagr
o3 .0?
.T
Lones, medion, occess no conlrol 4 Lones, medion, pqrtiol occess control 4 Lones, medion, occess full control
measuring the improvements. Table l! per 0.3-milc
curves.
N
o
9 6
@c)
R 3 98338
Averoge doily troffic,hundreds Fic' I5-3' Averagenumbcrofaccidentsper0.lmilesegmentonyuralhighwaysinohio,bynumber of lancs, medians,and accesscontrot l5-121. I
o o F g gFg o
thros
Tratftc
Accidents
417
type. Figure l5-4 givesthe composite connecticut, for Frorida,and ohio for four GDmmon types of highways. In both thesesetsof curves there are pronounced *: ^:?": of..accidentswith increase the ADr. rhus, rerating in :::::: 11 rcident rates to vehicre-miles traver may be accepted of as a good devicefor
-----
C o n v e n t i o n wlo - l o n e to F o u rl o n e f D i v i d e do u r - t o n e C o n t r o l l e d c e s so u r - l o n e oc t
o
9o@
@o
a N
o n
ooo sorO
oc) @9
o
N
o
O
oc) o
9 O @
oo
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Averogedoily troffic, hundreds
Fic' I 5-4' Average ""'t:"::J;:i:"J,:,,ff :":.i&*, [:ff:',
on rurarhighwavs in
measuring the relative safety or of the effectivenessof accident-reducing improvements. Table l5-19 is helpfurin indicatinghow the rerative accident ratesperyear per 0.3-mile segment increase with combinations of the desigrr elementsof grades, curves, intersections, structures. and Table l5-19 is supplemented Figs. r5-5 to 15-10 the composite by for of the three statesto show the accidentratesfor two-lanerural highways for a full range of ADT and different combinationsof the existence curves,grades, of intersections, and structures.
418
Traffic
Accidents
Traffic
Accidents
E
I E o
9 P E 6 E
---- - -- -
Puresgg6g115 Sgnents contoining curvqtur conloining g.ode Segments o Segments contqining intersections Sgments conloining slructures
oo -
o
N
oooooo o
9 6 @
@ O
Averoge doily trqllic, hundrcds
, q averaSc Rc. l5-7. Three-state highways showing the effecr of
FIc. I 5-5. Three-state averagenumber of accidents per O.3-mile segment rural two-lane on highways showing separatelythe effects of curves, grades, intersections, and structures
tl5-r21.
= l
o
9 6
E ---- - -CurveonlY Curvond grode Curveqnd inlersection Curw ond st,uclures a
.10 08 06 05 04 03
.o2
s?8388
-
I 888888
s 6 c 6 @ 6 0
AEro9cdoil, trollic,hundr:d: FIc. l5-6. Three-state average number of accidents per 0.3-mile segment on rural two-lane highways showing the effects of horizontal curves combined separately with grades, intersections, a n d s t r u c t u r e sI l 5 - 1 2 1 .
"
averaF { Frc. l5-8. Three-state highways showi4g the effects of I
Traffic
Accidents
419
o
.00 .80 .60 .50 40 20
9
.10 .08 .06 .05 .04 .03 .02
-_------
Grode o Grode nd curve o Grode nd inlerseclion Grqdeqnd skuctures
o o
ooo 9 0 @
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Avgroqg doily trollc. hundreds
Ftc. l5-7. Three-state averagenumber of accidentsper 0.3-mile segment rural two-lane on highways showing the effects of grades combined separatelywith curves, intersections, a n ds t r u c t u r eIs 5 - 1 2 1 . l
= l
9
00 80 .50 50 40 30 20
E
o s 6 @ 6 0
0
0 0 0 0 0 0 c o @ @ o hundreds
o o
6
ooo ooo
< O @
oo oo
@ O
Averoge doily kollc,
Ftc. l5-8. Three-state averagenumber of accidentsper O.3-milesegment rural two-lane on highways showingthe effectsof intersections combined separately with curves,grades,and s t r u c t u r eIs 5 - 1 2 1 . l
420
Traffic
AccidentC
Traffic
Accidents
z
E gl e o
E
E
a E
-------onlt Struclures ood Structures cuivotute ond grodient Strutures ondintrsctims Slructur6
o o
ooo ao@
o0 @o
lAl. From Table l5-2 for (j compute the ratios of (a) nonfd{ accidents. Use just the total li1 how such ratic{ ratios and suggest lA2. From Table l5-2 cci rural accident. Discuss the pn{ Make a similar analysisof Tablc I local streetsand roads. i la3. Discuss the relativc { human life for use in economic i death, (2) averageof life insum{ measures taken to prevent accila{ accidentaldeath, (5) average { of carnings less present worth of { and (7) others. l5-4. For the following o{ pcr mile which would be equh{ by constructinga fourJane rur{{ rural highway without access Oodt
on Ftc. I 5-9. Three-stateaveragenumber of accidentsper 0.3-mile segment rural twolane grades,and highways showing the effects of structures combined separately with curveqo intersectionsI 5-l 21. I
V e s t c h a r ga t e . . . . . . . . . . l 0 t 3 re period . Analysis InitialADT 20F..... 5,(m
E
'-c l E o
s
a
ADT annual growth ratc ADT composition,trucb
Itr
E
E
l5-5. Widcnirg I accidents 25 pcrc
vcti 100.000.000
*- -'gtode, sttuctutes ond Curve, - - - - Curve, grode, inkrsctong ond C{rve,inteGectb6,ond ltt*tures - -&o&, inle6ecti(ffi,ond skirtures Curw,Eode,inlercti(ffi,ond st.(lutes Puresgfltnts
.t e
E
damage only per ac.ilal
r 20.m)
Aaoqc
('qilt ttollic, hsdaG
per o.3-mile segmentonruraltwo{ane averagenumber of accidenrs Rc. l5-10. Three-state and highways, showing the effects of the combined presenceof curves, grades, intersections, structures [l5-121.