SU0002224 SSNL - Laserfiche WebLink

Home Browse Search

TABLE l LEVEL OF SERVICE CRITERIA FOR SIGNALIZED,UNSIGNALIZED AND ALL WAY STOP CONTROLLED INTERSECTIONS STOPPED DELAY/VEHICLE(SEC) LEVET.OF ALL-WAY SERVICE TYPE OF FLOW DELAY MANEUVERABILITY SIGNALIZED UNSIGNALIZED STOP A Stable Flow Very slight delay. Progression is very Turning movements are easily made, < 5.0 favorable, with most vehicles arriving during and nearly all drivers find freedom of the green phase and not stopping at all. operation. B Stable Flow Good progression and/or short cycle lengths. Vehicle platoons are formed. Many 5.1 - 15.0 5.1 - 10.0 5.1 - 10.0 More vehicles stop than for LOS A, causing drivers begin to feel somewhat higher levels of average delay. restricted within groups of vehicles. ` C Stable Flow Higher delays resulting from fair progression Back-ups may develop behind turning 15.1 -25.0 10.1 -20.0 11.0- and/or 1.0-and/or longer cycle lengths. Individual cycle vehicles. Most drivers feel somewhat 20.0 failures may begin to appear at this level. The restricted. number of vehicles stopping is significant, although many still pass through the intersection without stopping. D Approaching The influence of congestion becomes more Maneuverability is severely limited 25.1 -40.0 21.0-30.0 21.0- Unstable Flow noticeable. Longer delays may result from during short periods due to temporary 30.0 some combination of unfavorable progression, back-ups. long cycle lengths, or high volume-to-capacity ratios. Many vehicles stop, and the proportion of vehicles not stopping declines. Individual cycle failures are noticeable. E Unstable Flow Generally considered to be the limit of There are typically long queues of 40.1 -60.0 31.0-45.0 31.0- acceptable delay. Indicative of poor vehicles waiting upstream of the 45.0 progression, long cycle lengths, and high intersection. volume-to-capacity ratios. Individual cycle failures are frequent occurrences. F Forced Flaw Generally considered to be unacceptable to Jammed conditions. Back-ups from > 60.0 > 45.0 > 45.0 most drivers. Often occurs with over other locations restrict or prevent saturation. May also occur at high volume-to- movement. Volumes may vary capacity ratios. There are many individual widely, depending principally on the cycle failures. Poor progression and long downstream back-up conditions. cycle lengths may also he major contributing factors. References: lliglnvuy Capacity Manual, Special Report No. 209, Transportation Research Board, 1985. Highway Capacity Manual, Special Report No. 87, Highway Research Board, 1965. Trinity Baptist Church Project Page 7 Traffic Study