Improving capacity estimation of high volume on-street bus facilities with yield-to-bus rule

Effectiveness of an on-street bus facility depends on the general traffic volume that shares the lane with buses. The aim of this study is to better understand performance of an on-street bus facility by relating bus stop capacity with the adjacent lane traffic volume. The Transit Capacity and Quality of Service Manual (TCQSM) methodology estimates facility bus capacity based on critical stop operation. The theory is based on re-entry delay approach, where it is assumed that buses wait at the bus stop until there is no general traffic movement or queuing in the adjacent traffic lane. However, this theory does not reflect the influence of yield-to-bus (YTB) rule. Therefore, this research provides an improved understanding of critical bus stop operation on high volumes on-street bus facilities where the YTB rule applies. A microscopic simulation model is developed to model an off-line bus stop with two loading areas. The model is then used to observe bus stop capacity variations with increasing adjacent lane traffic volume. Two case scenarios are presented, one being the case where the bus stop is away from a signalized intersection and the second is the case where the bus stop is upstream of the signalized intersection. The simulation model demonstrates that inclusion of YTB rule allocates higher bus stop capacities in both cases. The model also shows that higher bus capacities are achievable due to elimination of re-entry delay.