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Metro Retimes Traffic Signals Countywide to Increase Road Capacity, Reduce Travel-Time Delays


Earlier this month, Metro Public Works completed an ambitious traffic-signal synchronization project to optimize and streamline the timing of 550 signals along 18 major pikes and corridors throughout Nashville.

“While we explore options to provide more choices to get around congestion, such as transit, bicycle and pedestrian trips, we still must continue improving the flow of roadway traffic as it stands today,” said Mayor Barry. “Retiming our signals is a prime example of available short-term solutions for addressing the many stresses put on our transportation system by Nashville’s rapid growth.”

The project aimed to implement signal-retiming plans countywide in order to increase Nashville’s road capacity without making major, costly changes to existing infrastructure. The project also reduced vehicle travel-time delays attributed to outdated infrastructure and signal-timing that did not reflect current, on-the-ground conditions. Intersection Times-of-Day plans were developed based on a fresh round of traffic-counts at each location, collected in the spring of this year when K-12 schools were still in session.

“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 Mayor Megan Barry. 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.

“While we anticipate that, on the whole, most Nashville-area motorists will notice only subtle changes in their daily commutes, Public Works will have cumulative data to show reduced delays – particularly along major arterials, where signals were retimed to be coordinated along the length of those routes,” said Chip Knauf, chief traffic engineer with Metro Public Works. “We’ll continue to monitor and adjust signal timings throughout the coming years to ensure our traffic operations strategy and technologies are meeting the changing needs of a dynamic and growing city.”

As part of this project, Metro Public Works’ traffic division collected before-and-after travel times, the results of which are currently being reviewed and will be published in a detailed report early next year.

In addition to retiming signals, MPW installed new controllers at 600 locations in order to improve system reliability, enable computerized interaction with full Bus Rapid Transit service planned for the future, decrease maintenance costs, and adjust signals in real-time as needed. Metro Public Works has additional signal re-timings underway on Old Hickory Boulevard, as well as a major, federally-funded project on Murfreesboro Pike that will prioritize signals to enhance MTA’s “BRT Lite” bus service.

Optimizing the timing of signals is considered a low-cost, high-benefit approach to mitigating urban traffic congestion. By deploying improved signal technology to maximize traffic progression on the local transportation system, traffic engineers can help to minimize stops, delays, fuel consumption, and pollution from tailpipe emissions. Other benefits include minimizing the diversion of traffic onto local and residential streets, and improving intersection safety.

Metro Public Works Signal Timing Corridor List