tte4004%20Chapter%201%2C2 - Highway Safety (pages 131-153)...

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Unformatted text preview: Highway Safety (pages 131-153) (pages Highway More than 500,000 people die worldwide More every year from road crashes The third most leading cause of death in the The US Around 40,000 road fatalities every year in Around the US The loss of lives and damaged caused by The road crashes amount to Billions of Dollars in societal cost The proposed new transportation bill in The congress SAFETEA puts more emphasis on transportation safety in the US Issues Involving Transportation Issues Safety “Accident” versus “Crash” Causes of a Crash. Example of the “Titanic” Causes Factors Involved in Transportation Crashes: Factors – The Driver – The Vehicle – The Roadway – The Environment This Chapter is focused on road design and traffic issues related to crashes Safety Programs Safety Airbags Airbags Alcohol: Deterrence & Enforcement Alcohol: Underage Drinking Underage Antilock Brakes Antilock Bumpers Bumpers Daytime Running Lights Daytime Large Trucks Large Motorcycle Helmet Use Laws Motorcycle Pedestrians Pedestrians Red Light Cameras Red Speed: Law Enforcement Speed: Teenagers: Graduated Driver Licensing Teenagers: U.S. driver licensing renewal procedures for older drivers U.S. Child restraint/belt use laws Child Helmet use laws by state Helmet 4Es 4Es –Engineering –Enforcement –Education –Environment Approaches to safety: Approaches –Reducing Accidents –Reducing Severity –Improving Crash Survivability –Programmatic Safety Efforts –Design Aspects of Safety Accident Data Collection Accident –Why need to collect frequency frequency severity severity location location type type Reporting Reporting –Source of Data –Manual Filing –Computer Record System Accident Statistics Accident –Types Occurrence: type and # Occurrence: Involvement: categories of Involvement: drivers and vehicles Severity: death, injury, and Severity: property damage only –Rates Population base Population –Area: registered vehicles –Licensed Drivers: hwy. mlg. Exposure Rate Exposure –vehicle-miles –vehicle-hours Severity Index Severity –Number of deaths per accident High Accident Locations High –Computer generated colored maps Hazardous Locations Identification Hazardous –Frequency –Rates: R1=(A)(106)/(365)(T)(AADT) R2=(A)(106)/(365)(T)(AADT)(L) Computing Crash Rates Computing 25 crashes recorded at an intersection 25 intersection Average daily volume is 7500 Average Rate per Million Entering Vehicles Rate RMEV = 25 X 106 / (7500 X 365) = 9.13 30 crashes occurred on a 10 mile section 30 section road in one year with an ADT of 8000 Rate per 100 Million Vehicle Miles Rate RMVM = 30 X 108 / (10 X 8000 X 365) = 102.74 Rc=Critical accident rate per million vehicle-miles Ra=Average accident rate M=million of vehicles passing a M=million point or MVM for a section Prob. 0.0050 0.0075 0.05 K 2.576 1.96 1.645 Identify High Crash Rate Location Identify Data collected at a particular non-signalized Data intersection for right-angle crash for 3 consecutive years resulted in 16 collisions. Statewide statistics for 40 similar intersections Statewide revealed a mean number of collisions of 12 and a standard deviation of 2.5 Expected range (with 95% confidence level)= Expected 12 ± 2.5 X 1.96 = (7.1,16.9) 16 collisions at the study site < 16.9 16 Right-angle crash is not overrepresented at the Right study site at 95% confidence limit Critical Crash Rate Method Critical CR = AVR + 0.5/TB + CR TF ( AVR/TB)0.50 CR = Critical crash rate…100MVM or MEV AVR = Average Crash Rate TB = Traffic Base… 100MVM or MEV TF = Test Factor… standard deviation at a given confidence level Critical Crash Rate Example Critical Urban arterial 0.20 mile long, AADT = 15,400 Urban 8 Fatal/Injury crashes + 15 PDO Statewide Stats: 375 per 100 MVM, 120 F/I, 255 PDO 1 F/I = 3 PDO, conduct analysis for 95% CI TB = (3X15,400X0.20X365)/(100X106) = 0.0337 TB AVR = 3X 120 + 255 = 615 eq. cr. per 100 MVM For 95% CI….. test factor = 1.96 CR = 615 + 0.5/.0337 + 1.96 √(615/.0337) = 895 Ratio of actual crash occurrence = (3X8 + 15)/.0337 = 1157 Crash Ratio = 1157/859 = 1.29 Crash 1.29>1 Safety problem likely to exist 1.29>1 •Before and After Analysis f A − fB Z= > 0.95 Improvement fB + f A Accident Reduction Significant Not Significant # of accidents before Sight Analysis Sight –collect data for accident frequency (How many years?) –physical characteristics –Condition & Collision Diagrams –Interpretation of results (reasons) sight distance, signal timing sight geometric, lighting, signing….. geometric, ...
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This note was uploaded on 01/13/2011 for the course CECS Transporta taught by Professor Essamradwan during the Spring '10 term at University of Central Florida.

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