Dynamic speed guidance for active highway signal coordination: roadside against in-car strategies

The effectiveness of signal coordination can be undermined by over-long spacing and different vehicle dynamic characteristics between neighbouring signal intersections in a signalised highway system. This study presents two dynamic speed guidance (DSG) strategies based on the traffic environment and facility deployment to congregate the traffic flow and optimise the arterial coordinated signal control system. One of them is the in-car display for individual guidance, and the other is the roadside display for group guidance. The two DSG strategies are calculated using the rolling horizon approach. A simulation platform that integrates data communication, traffic mobility and DSG application is programmed based on VISSIM, a microscopic simulation model. A section of Cao´an highway is used to assess the efficiency of two DSG strategies. The assessment results show that both the average stops and travel time of arterial vehicles can be optimised with the application of the two DSG strategies. In addition, the in-car strategy provides a significant benefit for on-board unit equipped vehicles, even in a low level of market penetration rate.