Saint Paul Arterial Roadway Traffic (SPART) Improvements – Signal Timing Optimization

Snelling Avenue, 7th Street, & Ford Parkway in Saint Paul, Minnesota

SRF retimed 62 intersections on three arterials across the City of Saint Paul. These corridors were selected for retiming to coincide with the addition of these intersections to the City’s new Centracs central signal control system.

Four new timing plans were developed using Synchro/SimTraffic and in-house spreadsheets to cover the weekday a.m. peak, midday peak, and p.m. peak periods along with a short cycle overnight plan. Pedestrian timing at each intersection was updated to comply with the 3.5-feet per second pedestrian walking speed guidance in the latest edition of the Minnesota Manual on Uniform Traffic Control Devices (MUTCD).

The corridors being retimed as part of the project are primarily 4-lane 30 mph urban arterials. In the CBD, cycle length was left unchanged and only small adjustments were made to offsets in order to minimize the impact to established progression patterns in this grid environment.

42 of the project intersections use Wapiti Type 170 signal controllers. The two intersections not using these controllers are the intersections at Snelling/University and 7th/Cedar. Econolite ASC/3 controllers are in use at these two intersections which are located along the route of the Central Corridor LRT line, planned to begin fare operations in 2014. SRF paid special attention to the impacts of future LRT operations as part of developing optimized timing for these intersections.

A unique aspect of this project was an assessment of the potential future benefit of Transit Signal Priority along the Snelling Avenue Arterial Bus Rapid Transit (Rapid Bus) Corridor. The analysis will look at two sets of timings – with and without an active TSP – and then estimate the amount of travel time saved by buses and the amount of extra delay experienced my motorists on other movements to assess the potential for net benefit in terms of person-delay and bus travel time. From these results, a ranking of all intersections on the corridor will be developed to help prioritize installation assuming a limited budget.

Project features include:

  • Coordinated signal timing on three corridors totaling 62 intersections
  • Provided training for city staff

Follow-up study evaluated potential benefits of transit signal priority (TSP) implementation

CLIENT:  City of Saint Paul