priority measures attempt to facilitate the movements of buses across
signalized intersections through temporary traffic signal timing adjustments.
The two main adjustments considered include extension of a green phase,
to avoid a bus being stopped by a red signal, and early green recall,
to reduce the delays incurred by a bus that is already stopped. Signal
timing adjustments can be sought to reduce overall travel times, improve
schedule adherence or provide more regular vehicle arrivals at bus
signal priority aim to benefit transit operations, it can also negatively
affect traffic performance, particularly on streets crossing transit
routes. To determine whether a proposed deployment may be beneficial
for transit vehicles while not causing significant negative traffic
impacts, the traditional approach has been to use simulation to evaluate
traffic and transit performance with and without transit signal priority.
This approach works well when considering deployments at an isolated
intersection or along a small number of arterial corridors, but not
when considering a large pool of potential deployment sites due to
the need to collect extensive data to build and calibrate the required
simulation models. For most transit agencies, the cost to collect
these data may be too great to consider using simulation to determine
the potential for benefits at each intended site. While alternative
to simulations are sought, there currently exist no analytical methods
that can be used to help determine which arterial corridors may best
benefit from transit signal priority deployments.
was faced by the Metropolitan Transportation Agency in Montreal, Canada,
which sought to evaluate the potential benefits associated with the
deployment of transit signal priority among a pool of 20 candidate
arterial corridors featuring relatively different roadway geometry,
traffic flow and transit operation characteristics. In response to
this need, a methodological framework that does not require the use
of simulation to evaluate the potential benefits associated with transit
signal priority deployments along specified arterials has been developed.
This methodology allow the evaluation and filtering of candidate arterials
based on a number of key roadway geometry, traffic signal control,
traffic flow and transit operation parameters. To minimize costs,
the methodology relies on the use of data that are commonly available
or that can be collected with relatively low effort and cost. At the
end of the evaluation, an implementation recommendation is provided
for each corridor, as well as for each intersection within a corridor.
Cost estimates to collect key missing data or improve the quality
of provided data are also provided.
Department of Civil and Environmental Engineering
3546 Engineering Building
Michigan State University
East Lansing, MI 48824-1226