21 ATTACHMENT 4 - Laserfiche WebLink

r. Analysis Methods The operations of roadway facilities are described with the term "level of service" (LOS). LOS is a qualitative description of traffic flow from a vehicle driver's perspective based on factors such as speed,travel time, delay, and freedom to maneuver. Six levels of service are defined ranging from LOS A (free-flow conditions)to LOS F (over-capacity conditions). LOS E corresponds to operations "at capacity."When volumes exceed capacity, stop-and-go conditions result, and operations are designated LOS F. Signalized Intersections Traffic conditions at signalized intersections were evaluated using methods developed by the Transportation Research Board (TRB),as documented in the Highway Capacity Manual 2000 Edition for vehicles.The HCM method calculates control delay at an intersection based on inputs such as traffic volumes, lane geometry, signal phasing and timing, pedestrian crossing times, and peak hour factors. Control delay is defined as the delay directly associated with the traffic control device (i.e., a stop sign or a traffic signal) and specifically includes initial deceleration delay, queue move-up time, stopped delay, and final acceleration delay. The relationship between LOS and control delay is summarized in Table 1. Unsignalized Intersections For unsignalized (all-way stop controlled and side-street stop controlled) intersections,the HCM 2000 method for unsignalized intersections was used.With this method, operations are defined by the average control delay per vehicle (measured in seconds).The control delay incorporates delay associated with deceleration, acceleration, stopping, and moving up in the queue.Table 2 summarizes the relationship between LOS and delay for unsignalized intersections.At side-street stop-controlled intersections, the delay is calculated for each stop-controlled movement,the left turn movement from the major street, as well as the intersection average.The intersection average delay and highest movement/approach delay are reported for side-street stop- controlled intersections.