Transit signal priority for Calgary's Green Line LRT

Abstract

The Green Line is a planned low floor, urban integrated Light Rail Transit (LRT) line in Calgary, Alberta. Future stages include extending the alignment to the north along Centre Street. This includes an 8 km section that is anticipated to have the LRT running down the middle of Centre Street, alongside the traffic, with the LRT passing through many signalized at-grade intersections.

Various traffic signal control strategies can be used for this type of LRT operation. The selection of the traffic signal control strategy is often a policy decision based on the competing needs for all modes using the corridor. While providing priority for the LRT may decrease travel time and increase ridership, it may, for example, provide unacceptable levels of delay for pedestrians trying to access the LRT stations. This paper will focus on the modelling and analysis of various options for this corridor, but the purpose of this paper is not to draw conclusions or recommendations.

Typical capacity evaluation software lack the capability to assess complex levels of roadway users interactions (LRT, vehicular traffic, and pedestrian traffic). Therefore, such analysis is often performed using microsimulation modelling as a tool to test various strategies and provide metrics for all modes to inform decision-makers. In order to determine how the LRT will interact with these at-grade intersections, different intersection control strategies have been modelled using PTV VISSIM’s software package.

Measures of effectiveness are determined and presented for vehicle, LRT and pedestrian operation throughout the corridor. The paper focuses on the pros/cons and trade offs for each scenario for all modes and the technology implications of implementing each scenario for the proposed alignment.