The delays for signalized intersections from the Highway Capacity Manual [using the Highway Capacity Software (HCS)], PASSER II-90, PASSER IV-96, Synchro, and CORSIM software were compared. An examination was made of how much delay reduction materialized when optimized signal settings were implemented. Synchro should not be compared with HCS unless certain precautions are taken to make the conditions analyzed in Synchro comparable with those analyzed in HCS. For both pretimed and actuated signals, if simultaneous phases exist in which one of them terminates ahead of the others, the results of HCS and Synchro are not comparable. For both pretimed and actuated signals, when the phases terminate simultaneously, whether the data are imported from Synchro or manually entered in HCS, the condition analyzed will not be comparable unless precautions are taken. Once these precautions were taken, control delays from Synchro and HCS were not significantly different for pretimed, uncoordinated signals. For actuated-uncoordinated and for actuated-coordinated controllers, the comparisons are not meaningful. Delays for optimized conditions for PASSER 11 and PASSER IV were not significantly different from the delays before optimization. However, for Synchro, the delays for optimized conditions were significantly lower than the delays before optimization. CORSIM was used to assess the impacts of the optimization. If optimized signal settings suggested by PASSER 11, PASSER IV, or Synchro are implemented, the delays for the optimized condition would not be significantly lower than the delays before optimization.
