This research used a micro-simulation model (VISSIM) and traffic analysis techniques to evaluate the impacts of enhanced Transit Signal Priority (TSP) at an isolated intersection in Charlottesville, Virginia. Researchers hypothesized that in situations where multiple buses approach simultaneously, enhanced TSP logic can resolve conflicting requests and reduce overall person-delay compared to conventional TSP.
The enhanced system, known as TSPCV-CR (TSP with Connected Vehicles accommodating Conflicting Requests), was designed to maximize transit TSP service rates and minimize adverse effects on competing traffic. The following scenarios were modeled.
- Without TSP
- Conventional TSP
Performance was evaluated at four congestion levels with three different conflicting scenarios.
TSPCV-CR reduced single bus delay up to 57 percent, and reduced average bus delay between 5 and 48 percent compared to conventional TSP. The range of improvement reflected volume/capacity ratios between 0.5 and 1.0, respectively.
TSPCV-CR gave preference to buses traveling in the direction with higher volume (major-street) but shifted priority to minor streets at near capacity conditions.
TSPCV-CR sometimes sacrificed the mobility of one bus line in order to achieve an overall reduction in delay.
Researchers indicated that the application could be used in real-time with a computation time of less than one second.