Decision Model for Resolving Conflicting Transit Signal Priority Requests

Resolving conflicting transit signal priority (TSP) requests has become an emerging topic in public transportation studies. The main objective of TSP is to reduce schedule deviation and enhance the reliability of bus service, whereas many previous studies have aimed at reducing priority delay. Furthermore, they did not take into account the element of waiting time experienced by passengers at bus stops. Therefore, this paper selects in-bus passenger delay and passenger waiting delay at next bus stops as the indexes to measure the priority level of TSP requests. Here, a decision model is proposed. It favors a bus with long delay and adds in-bus passenger delay and passenger waiting delay at next stops for buses requesting the same TSP actions. A case study is conducted to examine the performance of the proposed model, which was compared with the baseline model (no TSP), the conventional model (Model 1) using the first-in-first-service policy, and a typical optimization model (Model 2) developed in previous studies. Results show that the proposed model significantly outperformed the other three models. Specifically, the proposed model reduced average passenger waiting delay by 20.4%, 16.2%, and 12.2% over the baseline model, Model 1, and Model 2, respectively. The average in-bus passenger delay was reduced by 14.2% over the baseline method, by 10.3% over Model 1, and by 6.6% over Model 2. At the same time, the passenger delay of other vehicles for the proposed model was 8.8% and 4.8% lower than those of Model 1 and Model 2, respectively.