Offset effects on the capacity of paired signalised intersections during oversaturated conditions

Paired signalised intersections (PSI) are two closely signalised intersections with short distance between them as queue spillbacks and upstream intersection blockages occur. Due to queue spillbacks, the PSI have their own consideration regarding operational characteristics that are different from isolated intersections or coordinated networks. This paper explores the effects of timing plans offset on the movement capacity that passes through both intersections under several cases and situations. For this purpose, an analytical model is chosen to evaluate the movement capacities. The model has been coded and integrated into INBAR software, then it has been validated with results from the micro simulation software Vissim for various tests. A comparison of the two sets of results shows only minor deviations. The importance of offset is demonstrated through sensitivity analyses for different timing plan variables and parameters.