Can Transit Priority Measures be Justified?

摘要

The implementation of Transit Priority (TP) measures is often suggested as a means of increasing transit ridership and transit modal share (TMS) when increasing roadway capacity is problematic. TP is not magic, it is a trade-off; TP reallocates road space and/or signal green time to favour the movement of transit vehicles. Justifying implementation is often challenging for a number of reasons. Traditional traffic engineering optimization methods, performance measures (e.g. V/C ratio, vehicle delay) and evaluation procedures where designed for a single mode transportation system and they are inadequate to justify TP measures in a multimodal traffic environment. Furthermore, not all benefits and disbenefits of TP occur at the same time frame and a connection between short term operational objectives and long term planning objectives must be established. The proposed Transit Priority Index (TPx) serves that purpose. The City of Ottawa has implemented a number of Transit Priority measures over the last decade. These measures provide travel time and schedule reliability benefits to transit customers thus positively impact transit ridership. However, almost none of them could be justified by using the traditional traffic engineering evaluation framework. This paper identifies and discusses the major shortcomings of the traditional evaluation framework and proposes a different approach which connects the short term design and operational objectives with long term planning objectives.