Although research has shown that TSP is effective at improving bus speed and reliability, researchers have not extensively studied the effects of TSP on bus safety.

To help fill this gap, the research team studied the effects of TSP on vehicle safety. First, the team gathered ­detailed data about a TSP deployment at 30 signalized intersections along Metro Transit bus Route 5 in Minneapolis, Minnesota. The data included stop locations, geometric features of the bus stops, bus frequency, TSP requests, and crashes. Second, the team conducted a detailed regression analysis to understand if TSP use is associated with safer driving behaviors for the bus. While crashes on Route 5 were observed to decrease in the TSP deployment period, it is important to note that due to the low number of crashes, the team used surrogate safety measures, such as the roughness of bus travel. This measure quantifies the amount of sudden braking or stopping by analyzing the trajectory of the bus as it approaches and passes through the intersection.

In the end the team found:

• TSP helps smooth bus driving behavior (e.g., less abrupt stopping and deceleration).
• TSP likely improves bus safety.
• To further enhance safety benefits from TSP, bus operational features and road geometric design factors should be considered when implementing TSP.