Nashville Traffic Signal Synchronization


Perfect timing: Neel-Schaffer helps make traffic hum in Music City

Neel-Schaffer was the lead consultant for this ambitious traffic signal synchronization project to optimize and streamline the timing of 550 signals along 18 major travel corridors in the City of Nashville.

The $6 million project was accomplished over a condensed nine-month period, with a goal of increasing road capacity without making major changes to the existing infrastructure of one of America’s fastest-growing cities.

Neel-Schaffer engineers worked side-by-side with Metro Public Works, analyzing traffic counts to program some 300 different customized timing plans. Each corridor was programmed with a minimum of five custom plans – AM peak, Midday peak, PM peak, off peak, and weekend.

Metro Public Works installed new controllers at 600 locations, and three Neel-Schaffer engineers spent many hours programming the controllers.

“Metro Public Works is to be commended for stepping up to the plate and completing this critical countywide mobility project in just under a year,” said Nashville Major Megan Barry in a news release. According to the news release, a “complete traffic-count analysis and signal-retiming project of this size and scope can typically take more than two years, but at the Mayor’s urging, Metro Public Works expedited their timeline for completion.”

Neel-Schaffer and its team performed the following tasks to complete the project on schedule and within budget:

  • Hundreds of midblock and intersection turning movement counts in less than three months
  • Extensive field review and existing conditions inventory
  • Review and update all vehicle interval and pedestrian clearance timings
  • Create existing and proposed condition signal timing models using Synchro software
  • Evaluate and recommend proposed cycle length and corridor subsystem groupings
  • Develop multiple, sophisticated time-of-day coordinated signal plans
  • Develop and implement new standard traffic signal timing coding sheet for Metro Public Works new standard signal controller
  • Field observe and fine-tune all coordination plans
  • Conduct “before-after” travel time and delay studies on all project corridors

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