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TABLE C-l: LEVEL OF SERVICE CRITERIA FOR UNSIGNALIZED INTERSECTIONS, WITH CONTROL ON MINOR STREET ONLY Level of rvi Tunical QDerating Characteristics A Level of Service A describes a condition where the approach to an intersection appears quite open and turning movements are made easily. Little or no delay is experienced. The traffic operation can generally be described as excellent. B Level of Service B describes a condition where one or more critical movement approach to an intersection is occasionally fully used and short delays may be encountered. Many drivers begin to feel somewhat restricted within groups of vehicles. The traffic operation can generally be described as very good. C Level of Service C describes a condition where one or more critical movement approach to an intersection is often fully used and queuing may occur. The traffic operation can generally be described as good with average traffic delays. D Level of Service D describes a condition of increasing restriction and fewer gaps in the major street traffic flow,causing substantial delays and queues of vehicles on critical movement approaches to the intersection during short times within the peak period. The expected delay for minor street traffic is long;however, traffic operation can generally be described as fair. E Level of Service E describes the condition at which capacity of particular critical movement(s)is reached. It represents the most vehicles that any particular critical movement can accommodate;however,overall intersection operation may continue to operate at acceptable levels of service. At capacity there may be long queues of vehicles waiting up-stream of the critical movement.These vehicles may experience very long delays and potentially interfere with major street traffic flows. The traffic operation can generally be described as poor. F Level of Service F represents a jammed condition. Insufficient gaps restrict the movement of vehicles out of one or more critical movement to the intersection. Extremely long delays occur, and drivers may select smaller-than-usual gaps, potentially affecting other traffic movements at the intersection. In such cases, safety may be a problem. This condition usually warrants improvement to the intersection. SOURCE: Environmental Science Associates,Inc. from Highway Capacity Manual, Special Report 209,Transportation Research Board, 1985.