Transit Signal Priority in San Antonio’s metropolitan transit system decreases travel time by up to 20 percent.

Transit Signal Priority feature helps improve bus' reliability

San Antonio,Texas,United States

Summary Information

The VIA Primo transit line began operations in December 2012 and was the San Antonio region’s first Bus Rapid Transit (BRT) line. The Primo buses are modern-style, have a higher capacity (60 ft. long buses as opposed to the standard 40-ft VIA buses) and are powered by compressed natural gas.

Most notably, the Primo BRT system features a transit signal priority (TSP) solution that uses "virtual" GPS-based detection zones- the first of its kind in the U.S. The virtual detection zones are installed digitally on city traffic servers and, unlike most BRT systems, do not require emitters or hardware at every intersection. The virtual zones provide flexibility as they can be easily adjusted in response to changes in traffic flow due to special events or construction.
When a bus is in a virtual detection zone, the on-board GPS-location based computer will automatically send a signal priority request to the traffic management system. The request is then relayed to the intersection traffic controller which requests the traffic system to provide a green light for the approaching transit vehicle to help keep it on schedule.

  • The BRT system’s transit signal priority (TSP) feature helps the Primo vehicles adhere to their schedules and thus improves reliability.
  • Since its inception, the TSP system has helped reduce travel times by 15-20 percent.

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TSP in San Antonio BRT line reduces travel time by 15-20 percent

Published By: METRO Magazine



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Goal Areas


Typical Deployment Locations

Metropolitan Areas


bus priority, traffic signals, TSP

Benefit ID: 2015-01005