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APPENDIX A EXPLANATION OF LEVEL-OF-SERVICE CONCEPT Introduction The Traffic Forecasting Model and Traffic Simulation Model can be used to calculate congestion levels at the City's intemections under various land development, regional growth, and roadway network scenarios. The traffic model summarizes congestion levels at intersections in terms of Level-of-Service or LOS, with LOS A being very good and LOS F being very uncomfortable. This descriptive "level-of-service" is related to the delay vehicles encounter at an intersection. The City uses a standard methodology for calculating LOS, the 2000 Highway Capacity Manual methodology which uses many intersection conditions, especially traffic volumes, in translating the intersection's operation into a LOS category and average delay per vehicle. LOS Control Delay Per Vehicle A 510 seconds B >10 and _<20 seconds C >20 and <35 seconds D >35 and <55 seconds E >55 and_<80 seconds F >80 seconds Control Delay represents the amount of time a vehicle takes to enter an intersection in excess of normal travel time under free-flow conditions. This delay is associated with the operation of the traffic control device present at the intersection and a motorist's interaction with other motorists also trying to enter the intersection. Comparing the number of LOS A's, B's, and C's, etc. resulting from each land use and roadway network change only tells part of the story. For example, an intersection might he LOS C in one scenario with 21 seconds of delay. It might also be LOS C under another land development and roadway network scenario but have 35 seconds of delay. This represents a 67 percent increase in delay at this intersection even though the LOS remained at "C". Also, a typical drive from a home to a destination in Pleasanton requires drivers to travel along multiple roadways and through several intersections, with delay changing by different degrees all along the route traveled under various land use and roadway network scenarios. It can thus be more descriptive of changing driving conditions under each land use and roadway network change scenario to look at travel time and delay citywide instead of only looking at one intersection at a time. The traffic model routes traffic along City, Th-Valley, and regional roadways by calculating travel times along all available routes connecting the beginning of a trip to the trip's destination. As the traffic from local and regional land development increases, travel time increases as roadways and intersections become more congested. The traffic model uses this information to continually recalculate driving times along the various roadway routes available and re-routes