|A capacity analysis is performed as part of a traffic impact study. The operational characteristics of an intersection are calculated using SynchroTM 6 and HCS 2000 traffic software. HCS utilizes the methodology established within the Highway Capacity Manual (HCM) 2000. SynchroTM utilizes the HCM and also the Intersection Capacity Utilization (ICU) 2003 method. The measure of highway capacity is typically presented by addressing the intersection Level of Service.
The HCM method determines Level of Service by calculating the delay time experienced by vehicles approaching the intersection. HCM Level of Service is rated on a scale of A to F, Level of Service A being a condition of very low delay and Level of Service F being a condition of long delays. The ICU method gives insight into how an intersection is functioning and how much extra capacity is available to handle traffic fluctuations. ICU Level of Service is rated on scale of A to H, Level of Service A being a condition of no congestion with a large reserve capacity and Level of Service H being over capacity with long periods of congestion.
The two methods are closely interrelated and Synchro provides both the HCM and ICU Levels of Service. Synchro also allows data from multiple intersections to be input together as one network in order to determine the effects the traffic from each intersection will have on the adjacent nearby intersections in a neighborhood or along an entire traffic corridor.