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APPENDIX In order to better understand how the intersections operate ITom an overall traffic capacity standpoint, capacity analyses were perfonned using the methodology presented in the Highway Capacity Manual. Capacity analyses detennine how well or poorly an intersection is operating. Capacity analysis results are presented in tenns oflevel of setvice, which is defined in terms of traffic delay at the intersection, and ranges ITom an A to an F letter grade. . Level of setvice A corresponds to a iTee flow condition with motorists virtually unaffected by the intersection control mechanism. For a signalized or an un signalized intersection, the average delay per vehicle would be approximately 10 seconds or less. . Level of setvice B represents stable flow with a high degree of ITeedom, but with some influence ITom the intersection control device and the traffic volumes. For a signalized intersection, the average delay ranges nom 10 to 20 seconds. An unsignalized intersection would have delays ranging from 10 to 15 seconds for this level. . Level of setvice C depicts a restricted flow which remains stable, but with significant influence from the intersection control device and the traffic volumes. The general level of comfort and convenience changes noticeably at this level. The delay ranges iTom 20 to 35 seconds for a signalized intersection and iTom 15 to 25 seconds for an unsignaIized intersection at this level. . Level of setvice D corresponds to high-density flow in which speed and freedom are significantly restricted. Though traffic flow remains stable, reductions in comfort and convenience are experienced. The control delay for this level is 35 to 55 seconds for a signalized intersection and 25 to 35 seconds for an unsignalized intersection. For most. agencies in the Twin Cities area, level of setvice D represents the minimal acceptable level of setvice for regular daily operations. . Level of setvice E represents unstable flow of traffic at or near the capacity of the intersection with poor levels of comfort and convenience. The delay ranges from 55 to 80 seconds for a signalized intersection and iTom 35 to 50 seconds for an unsignalized intersection at this level. . Level of service F represents forced flow in which the volume of traffic approaching the intersection exceeds the volume that can be served. Characteristics often experienced include: long queues, stop-and-go waves, poor travel times, low comfort and convenience, and increased accident exposure. Delays over 80 seconds for a signalized intersection and over 50 seconds for an unsignalized intersection correspond to this level of setvice. Centre Poinfe Business Park -20 - January 15,2001