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Eugene Water & Electric Board (EWEB) Master Planned Development Appendix B APPENDIX 6 LEVEL -OF- SERVICE CONCEPT October 2012 Level of service (LOS) is a concept developed to quantify the degree of comfort (including such elements as travel time, number of stops, total amount of stopped delay, and impediments caused by other vehicles) afforded to drivers as they travel through an intersection or roadway segment. Six grades are used to denote the various level of service from "A" to "F ".1 Signalized Intersections The six level -of- service grades are described qualitatively for signalized intersections in Table B1. Additionally, Table B2 identifies the relationship between level of service and average control delay per vehicle. Control delay is defined to include initial deceleration delay, queue move -up time, stopped delay, and final acceleration delay. Using this definition, Level of Service "D" is generally considered to represent the minimum acceptable design standard. Table B -1 Level -of- Service Definitions (Signalized Intersections) Level of $ervice Average Delay per Vehicle Very low average control delay, less than 10 seconds per vehicle. This occurs when progression is extremely favorable, and most vehicles arrive during the green phase. Most vehicles do not stop at all. Short cycle lengths A may also contribute to low delay. Average control delay is greater than 10 seconds per vehicle and less than or equal to 20 seconds per vehicle. This generally occurs with good progression and /or short cycle lengths. More vehicles stop than for a level of service A, B causing higher levels of average delay. Average control delay is greater than 20 seconds per vehicle and less than or equal to 35 seconds per vehicle. These higher delays may result from fair progression and /or longer cycle lengths. Individual cycle failures may begin to appear at this level. The number of vehicles stopping is significant at this level, although many still pass C through the intersection without stopping. Average control delay is greater than 35 seconds per vehicle and less than or equal to 55 seconds per vehicle. The influence of congestion becomes more noticeable. Longer delays may result from some combination of unfavorable progression, long cycle length, or high volume /capacity ratios. Many vehicles stop, and the proportion D of vehicles not stopping declines. Individual cycle failures are noticeable. Average control delay is greater than 55 seconds per vehicle and less than or equal to 80 seconds per vehicle. This is usually considered to be the limit of acceptable delay. These high delay values generally (but not always) indicate poor progression, long cycle lengths, and high volume /capacity ratios. Individual cycle failures are frequent E occurrences. Average control delay is in excess of 80 seconds per vehicle. This is considered to be unacceptable to most drivers. This condition often occurs with oversaturation. It may also occur at high volume /capacity ratios below 1.0 with many individual cycle failures. Poor progression and long cycle lengths may also contribute to such high delay F values. ' Most of the material in this appendix is adapted from the Transportation Research Board, Highway Capacity Manual, (2000). I / Kittelson & Associates, Inc. B -2