Modeling effort shows that Transit Signal Priority can reduce bus travel times up to 43 percent with minimal impacts on non-transit traffic.

The simulation found that benefits extended beyond just transit vehicles.

Date Posted
04/23/2019
Identifier
2019-B01362
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Evaluation of Transit Signal Priority Implementation for Bus Transit along a Major Arterial Using Microsimulation

Summary Information

Transit Signal Priority (TSP) is a traffic management strategy that allows transit vehicles approaching signalized intersections to receive preferential treatment via shortened or lengthened signal phases to reduce delay time. It is a topic of particular conversation because of advances in connected and automated vehicle (CAV) technologies that allow equipped transit vehicles to more directly and accurately communicate with eligible intersections.



Researchers from Qatar University performed a simulation to investigate the effects of TSP along a major arterial, in order to better understand how the strategy affects routes with significant traffic. The model, which used historical traffic data from the 2016 Qatar Strategic Transport Model, was based on a real section of road in Doha, Qatar, that contains three public transportation routes and four intersections. The modeling software VISSIM was used.



Two different strategies were examined: "early green," in which signals truncate the red time in order to switch to green by the time the transit vehicle is expected to arrive at the intersection, and "green extension," in which the green time is extended by up to 10 seconds to allow the transit vehicles to pass through the intersection. Three different hours were evaluated: Peak AM, Peak PM, and Peak Midday.

FINDINGS

The results of the analysis found a reduction of transit vehicle travel time between 34 and 43 percent, depending on non-transit traffic conditions. The benefit is greatest when overall traffic demand is low.

The implementation of TSP actually reduced the average delay per non-transit vehicle. This was likely the result of extended phases that benefitted both transit and non-transit vehicles traveling in the same direction where TSP was implemented. In some cases, the delay reduction exceeded 40 percent. Despite the significant delay reduction in most cases, there were some intersections that experienced a slightly higher delay of 5 percent.

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