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Appendix F Transportation Analysis 4. Peak Hour Level of Service Definition Level of Service is a qualitative indication of the level of delay and congestion experienced by motorists using an intersection. Levels of service are designated by the letters A through F, with A being the best conditions and F being the worst (in terms of congestion and delay). LOS A, B, C and D are considered to have congestion levels in the acceptable range, while LOS E and F are considered unacceptable. At unsignalized intersections where only the minor street approaches are controlled, most of the major street traffic would not be subject to delay and would, by definition, have acceptable conditions. The major street left-turn movements and the minor street movements are all susceptible to delay of varying degrees. Generally, the higher the major street traffic volumes, the higher the delay for the minor movements. The LOS calculation methodology from the Highway Capacity Manual (HCM), Transportation Research Board, 2000, provides a delay value and level of service for each of these minor movements at the intersection. Table Fl shows the average delay criteria used to determine the level of service at the unsignalized intersections. At signalized intersections, the HCM signal operations method is used to determine the level of service, based on City standards. The LOS calculation methodology provides a single delay value and level of service for the intersection as a whole. The method determines an average control delay per intersection for the intersection. The delay criteria for signalized intersection levels of service are shown in Table F2. Table Fl Level of Service Criteria Unsignalized Intersections Level of Service A B 10.0 15.0 25.0 35.0 50.0 D E F 0.0 10.1 15.1 25.1 35.1 >50.0 Weighted average delay Source: Highway Capacity Manual 2000 F5