tte4004%20Chapter%202%2C8 - Intersection Control...

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Unformatted text preview: Intersection Control Intersection Manual on Uniform Traffic Control Manual Devices (MUTCD) General Principles: General –Fulfill a need –Command attention –Convey a clear message –Command respect –Give adequate time for response Five Considerations Five –Design –Placement –Operation –Maintenance –Uniformity Conflict Points at 4-legged Conflict Intersection Conflicts: 4 between competing Thru 8 LT/Thru 4 between competing LT Types of Intersection Controls Types Level I: Passive Control-Basic Level Rules of the road –No control –Guide signs only –Warning Signs with or without guide signs –Level II: Assignment of Rightof-way to major street YIELD control YIELD Two-Way STOP control Two All-Way STOP control All –Level III: Positive alternate assignment of exclusive ROW Traffic Signals Traffic –Two phase –Multiphase Traffic control agent/officer Traffic MUTCD WARRANTS MUTCD Warrant 1-Minimum vehicular Warrant volume. Warrant 2-Interruption of Warrant continuous traffic. Warrant 3-Minimum pedestrian Warrant volume. Warrant 4-School crossings. Warrant Warrant 5-Progressive movement. Warrant Warrant 6-Accident experience. Warrant Warrant 7-Systems. Warrant Warrant 8-Combination of Warrant warrants. Warrant 9-Four Hour Volumes. Warrant Warrant 10-Peak Hour Delay. Warrant Warrant 11-Peak Hour Volume. Warrant Warrant 1, Minimum Warrant Vehicular Volume The warrant is satisfied when, for The each of any 8 hours of an average day, the traffic volumes given in the table below exist on the major street and on the higher-volume minor street approach to the intersection. Major St. Minor St. VPH Total VPH One Direction 1 1 500 150 1 600 150 2 or more 2 or more 2 or more 600 200 1 2 or more 500 200 Warrant 2, Interruption of Warrant Continuous Traffic The warrant is satisfied when, for The each of any 8 hours of an average day, the traffic volumes given in the table below exist on the major street and on the higher-volume minor street approach to the intersection. Major St. Minor St. VPH Total VPH One Direction 1 1 750 75 2 or more 1 900 75 2 or more 2 or more 900 100 1 2 or more 750 100 Warrant 3, Minimum Warrant Pedestrian Volume The warrant is satisfied where the The pedestrian volume crossing the major street at an intersection during an average day is: 100 or more for any 4 hours; or 190 or more during any one hour Warrant 4, School Crossing Warrant A traffic control signal may be traffic warranted when the number of adequate gaps in the traffic stream during the period when the children are using the crossing is less than the number of minutes in the same period Pedestrian indications shall be Pedestrian provided at least for each crosswalk established as a school crossing. At an intersection, the signal At normally should be semi-trafficactuated At non-intersection crossings, the At signal should be pedestrian actuated. Warrant 6, Accident Experience Warrant The Accident Experience warrant is The satisfied when: Adequate trial has failed to reduce Adequate the accident frequency; and Five or more reported accidents, of Five types susceptible to correction by traffic signal control, have occurred within a 12-month period, and The signal installation will not The seriously disrupt progressive traffic flow. Warrant 9, Four Hour Volume Warrant Warrant is satisfied when each of Warrant any four hours of an average day the plotted points representing the vehicles per hour on the major street (total of both approaches) and the corresponding vehicles per hour on the higher volume minor street approach (one direction only) all fall above the curve shown next . Warrant 10, Peak Hour Delay Warrant It is intended for application where It traffic conditions are such that for one hour of the day minor street traffic suffers undue delay in entering or crossing the major street. The peak hour delay warrant is satisfied when the conditions given below exist for one hour (any four consecutive 15minute periods) of an average weekday. The total delay experienced by the The traffic on one minor street equals or exceeds four vehicle-hours for a one-lane approach and five vehicle hours for a two-lane approach, and The volume on the same minor The street approach (one direction only) equals or exceeds 100 vph for one moving lane of traffic or 150 vph for two moving lanes, and The total entering volume serviced The during the hour equals or exceeds 800 vph for intersections with four (or more) approaches or 650 vph 650 vph for intersections with three approaches. Warrant 11, Peak Hour Volume Warrant The peak hour volume warrant is The also intended for application when traffic conditions are such that for one hour of the day minor street traffic suffers undue traffic delay in entering or crossing the major street. The peak hour volume warrant is The satisfied when the plotted point representing the vehicles per hour on the major street (total of both approaches) and the corresponding vehicle per hour of the higher volume minor street approach (one direction only) for one hour (any four consecutive 15minute periods) of an average day falls above the curve. Signal Phasing Schemes NO LT BAY Two Phases Three Phases Signal Phasing Schemes LT BAY Two Phases Three Phases OR Phase Color Indications Phase •Change Interval at Traffic Signals Dilemma Zone: Dilemma It is a zone within which the driver It can not stop or proceed through the intersection safely. Why? x = v0t + (v0)2/2a y = needed time to stop = x/ v0 = needed t + v0/2a z = needed time to go through = needed (d + w + L)/ v0 If d < x, a dilemma zone occurs If Clearance Time = t + v0/2a + Clearance (w + L)/ v0 Example: An intersection 70 ft Example: wide, Is there a dilemma zone exists if a clearance period of 3 seconds is applied? V0 = 45 Time = 1 + 45/(2)(10) + (70+20)/45 Time = 5.25 seconds (3)(45) = d + 70 + 20, d = 45 feet (3)(45) x = 45(1) + (45)2/(2)(10) = 146 feet Dilemma Zone = 146-45 = 101 feet Dilemma Zone 101 feet 45 Feet Webster’s Method for timing Webster’s Traffic Signal C0 = Optimum Cycle Length L = Total Lost Time = ℓ * number of phases ∑ = Summed for all phases Φ Q = Max Flow per lane group Max Saturation S = Saturation Flow Rate on Lane Group 1.5L + 5 C0 = Q 1− ∑ ( ) S ℓi = Gai + τi + Gei – ℓi = Lost time per phase – Gai = Actual Green time for phase i – τi = Yellow time for phase i – Gei = Effective Green time for phase i L = ∑ ℓi + R – R = Total all-red time Gte = C - L Minimum Green Time Minimum Gp = 3.2 + L/Sp + [ 2.7 (Nped)/WE] WE>10 Feet Gp = 3.2 + L/Sp + ( 0.27 Nped) WE≤10 Feet – L = Crosswalk length – Sp = Average speed = 4 fps – 3.2 = Pedestrian start up time – WE = Effective Crosswalk width – Nped = Number of pedestrians crossing during the interval Webster’s Method Example Webster’s 109 ◄▼ 75 ▼ 25 ► ◄ ◄ 222 464 464 ▲ ► ► PHF=0.95 ▼ 321 321 128 ◄ ▲ ▲► 352 100 206 Webster’s Method Example…Cont. Webster’s 115 ◄▼ 79 ▼ 26 ► ◄ ◄ 234 488 488 ▲ ► ► PC Equivalent ▼ 338 338 135 ◄ ▲ ▲► PHF = 0.95 371 105 217 Webster’s Method Example…Cont. Webster’s Phase A Lane Grou 1 2 q 234 976 s 1615 3700 q/s 0.145 0.264 Y Phase B 12 676 135 3700 1615 0.183 0.084 Phase C 12 26 194 1615 3700 0.016 0.052 Phase D 12 371 322 1615 3700 0.230 0.087 SUM 0.729 0.264 0.183 0.052 0.23 Webster’s Method Example…Cont. Webster’s C0 1 .5 L + 5 = Q 1− ∑ ( ) S C0 = {(1.5X14)+}/(1-0.729) = 59.9 seconds Use 100 second cycle length Use G = C-L = 100-14 = 86 G1 = (Y1/Y)XG = (.264/.729)X86 = 31 seconds Actual Green Time for Phase 1 = 31 + 3.5-3 Actual = 32 seconds Actual Green Time for Phase 2 = 22 seconds Actual Actual Green Time for Phase 3 = 7 seconds Actual Actual Green Time for Phase 4 = 27 seconds Actual ...
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