Quantifying the Mobility and Safety Benefits of Transit Signal Priority

Authors

MD Sultan AliFollow

Document Type

Dissertation

Degree

Doctor of Philosophy (PhD)

Major/Program

Civil Engineering

First Advisor's Name

Priyanka Alluri

First Advisor's Committee Title

Committee chair

Second Advisor's Name

Albert Gan

Second Advisor's Committee Title

Committee member

Third Advisor's Name

Mohammed Hadi

Third Advisor's Committee Title

Committee member

Fourth Advisor's Name

Xia Jin

Fourth Advisor's Committee Title

Committee member

Fifth Advisor's Name

Florence George

Fifth Advisor's Committee Title

Committee member

Sixth Advisor's Name

Thobias Sando

Sixth Advisor's Committee Title

Committee member

Keywords

Transit signal priority, mobility, transferability, safety

Date of Defense

6-29-2021

Abstract

The continuous growth of automobile traffic on urban and suburban arterials in recent years has created a substantial problem for transit, especially when it operates in mixed traffic conditions. As a result, there has been a growing interest in deploying Transit Signal Priority (TSP) to improve the operational performance of arterial corridors. TSP is an operational strategy that facilitates the movement of transit vehicles (e.g., buses) through signalized intersections that helps transit service be more reliable, faster, and more cost-effective. The goal of this research was to quantify the mobility and safety benefits of TSP. A microscopic simulation approach was used to estimate the mobility benefits of TSP. Microscopic simulation models were developed in VISSIM and calibrated to represent field conditions. Implementing TSP provided significant savings in travel time and average vehicle delay. Under the TSP scenario, the study corridor also experienced significant reduction in travel time and average vehicle delay for buses and all other vehicles. The importance and benefits of calibration of VISSIM model with TSP integration were also studied as a part of the mobility benefits. Besides quantifying the mobility benefits, the potential safety benefits of the TSP strategy were also quantified.

An observational before-after full Bayes (FB) approach with a comparison-group was adopted to estimate the crash modification factors (CMFs) for total crashes, fatal/injury (FI) crashes, property damage only (PDO) crashes, rear-end crashes, sideswipe crashes, and angle crashes. The analysis was based on 12 corridors equipped with the TSP system and their corresponding 29 comparison corridors without the TSP system. Overall, the results indicated that the deployment of TSP improved safety. Specifically, TSP was found to reduce total crashes by 7.2% (CMF = 0.928), FI crashes by 14% (CMF = 0.860), PDO crashes by 8% (CMF = 0.920), rear-end crashes by 5.2% (CMF = 0.948), and angle crashes by 21.9% (CMF = 0.781). Alternatively, sideswipe crashes increased by 6% (CMF = 1.060), although the increase was not significant at a 95% Bayesian credible interval (BCI). These results may present key considerations for transportation agencies and practitioners when planning future TSP deployments.

Identifier

FIDC010189

Recommended Citation

Ali, MD Sultan, "Quantifying the Mobility and Safety Benefits of Transit Signal Priority" (2021). FIU Electronic Theses and Dissertations. 4713.
https://digitalcommons.fiu.edu/etd/4713