Laserfiche WebLink
Traffic Operations <br />The operating conditions of transportation facilities, such as roadways, traffic signals, roundabouts and <br />stop -controlled intersections, are evaluated based on the relationship of the theoretical capacity of a <br />facility to the actual traffic volume on that facility. Various factors affect capacity including travel speed, <br />roadway geometry, grade, number of travel lanes, and intersection control. The current standards for <br />evaluating capacity and operating conditions are contained in Highway Capacity Manual'. The <br />procedures describe operating conditions in terms of driver delay represented as a Level of Service <br />(LOS). Operations are given letter designations with "A" representing the best operating conditions and <br />"F" representing the worst. Generally, level of service "D" represents the threshold for acceptable overall <br />intersection operating conditions during a peak hour. The Chart below summarizes the level of service <br />and delay criteria for signalized and unsignalized intersections. <br />Level of Service <br />Description <br />Delay (sec) <br />Signalized <br />Unsignalized/ <br />Roundabout <br />A <br />Primarily free -flow operation. <br />0-10 <br />0-10 <br />- - - - - - - - - - - - - - - -- <br />B <br />Reasonably unimpeded operation. <br />>10-20 <br />>10-15 <br />--- - - - - -- — - - - -- <br />Kill <br />C <br />operation. The ability to maneuver is <br />more restricted than LOS B. <br />>20-35 <br />>15 25 <br />_ _ _ _ _ _ _ _ _ _Stable <br />' L,v <br />D <br />Less stable operation. Small increases in flow <br />may cause large increases in delay and reduced <br />speeds. <br />>35-55 <br />>25-35 <br />-6--* ;001 ;001 <br />----------------- <br />o_%' co ; <br />Unstable operation. Low speeds and <br />considerable delay. <br />>55-80 <br />>35-50 <br />-rV 151 _ 001 - <br />( <br />7 . <br />,. (! Lam_-- <br />Congested operation. High delay and extensive <br />queuing. <br />>80 <br />>50 <br />For side street stop -controlled intersections special emphasis is given to providing an estimate for the <br />level of service of the minor approaches. Traffic operations at an unsignalized intersection with side <br />street stop -control can be described two ways. First, consideration is given to the overall intersection <br />level of service. This takes into account the total number of vehicles entering the intersection and the <br />capability of the intersection to support these volumes. Second, it is important to consider the delay on <br />the minor approaches, since the mainline does not have to stop. It is common for intersections with higher <br />mainline traffic volumes to experience increased levels of delay and poor level of service on the side <br />streets. <br />1 Highway Capacity Manual (HCM), Transportation Research Board, 61h Edition <br />7 I P a g e Jackson Hills Apartments — Phases 2-4, Elk River, MN <br />