Complementing Transit Signal Priority with speed and dwell time extension advisories

Transit Signal Priority (TSP) makes Public Transport (PT) more competitive to the private car by facilitating the movement of PT vehicles across signalised intersections. However, the acceptance of TSP is limited, as its application can result in delays to the general traffic. In the future traffic signals will broadcast Signal Phase and Timing (SPaT) status information to nearby vehicles. Thanks to this, TSP could be complemented with in-vehicle systems such as Green Light Optimal Speed Advisory (GLOSA) and Green Light Optimal Dwell Time Advisory (GLODTA). They allow a bus to pass through signalised intersections during a green phase, without modifying signal timings. Therefore they do not create delays to the general traffic. The objective of this paper is to analyse how the two systems can complement TSP and to which extend they can be used instead of TSP. Using computational experiments we demonstrate that although signal priority provides greater travel time improvement, the two advisory systems offer similar advantages in terms of reducing the number of stops and delay time at traffic signals.