Conduct bench testing prior to field installation of transit signal priority (TSP) equipment to verify functionality between detectors, signal controllers, phase selectors, and cabinet design.

Pilot deployment of transit signal priority in Chicago identified multiple considerations that may help inform future deployments.

Date Posted
09/26/2017
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Identifier
2016-L00729

CTA Transit Signal Priority (TSP) Initiative: Evaluation Report for Western Avenue TSP Demonstration

Summary Information

This evaluation was conducted to identify the benefits of transit signal priority (TSP) at 10 TSP-equipped intersections for Route X49 buses and Route 49 buses along Western Avenue in Chicago. The evaluation was performed by comparing the Measures of Effectiveness (MOEs) for travel time, delay, time deviated from schedule, and number of delayed buses between before and after signal optimization, and before and after TSP implementation with data collected in the field.

Lessons Learned

The lessons learned from the field installation, testing, and evaluation of the TSP system:

  • Select a TSP technology compatible with existing traffic signal controllers and the existing bus AVL systems and communications infrastructure.
  • Coordinate technology selection and deployment if multiple transit operators are involved.
  • Relocate near-side bus stops to far-side on TSP intersections. Since the TSP request terminates when the bus doors open at a near-side stop, the green extension ends after the bus stops for boarding the passengers.
  • Deploy TSP systems at intersections where a minimum of 10 seconds green time could be taken from the minor street and used for early green TSP applications.
  • Deploy TSP systems at intersections with a reasonable spacing along a corridor so delayed buses have opportunities to resume adherence to the schedule.
  • TSP systems are not recommended at saturated intersections where heavy traffic demand is served and capacity is reached. These intersections are unable to provide additional green time.
  • Early green TSP systems are not recommended at intersections where a leading left-turn phase is served for major streets.
  • Provide training for bus operators so they actually experience and witness TSP benefits.
  • Emitters must be installed with a robust bracket to prevent them from losing alignment due to long-term vibration. Communication between emitters and detectors may be lost if emitters' positions are not properly aligned.
  • Conduct bench testing prior to field installation to ensure functionality between phase selectors, detectors, signal controllers, and cabinets.
  • Assigning unique vehicle identifiers to each bus to helps monitoring and evaluating system performance.