Four different Natoma Street intersections will be first to activate under city’s pilot program Sept. 8
A new look comes to life o traffic signals along select Folsom streets next week as the city prepares to activate its first flashing yellow arrows, putting a pilot program approved by the City Council into operation after months of preparation and construction.
The new flashing yellow arrow signals will be activated Tuesday, Sept. 8, at four intersections along Natoma Street: Prison Road, Wales Drive, Stafford Street and Coloma Street.
The change introduces a new option for motorists making left turns. A flashing yellow arrow allows drivers to turn left after yielding to oncoming traffic, bicyclists and pedestrians, providing additional opportunities to make a turn when conditions are safe rather than requiring motorists to wait for a protected green arrow.
Drivers will continue to see the standard red, yellow and green signal indications they are accustomed to. The flashing yellow arrow adds another phase to the signal operation, allowing a left turn while opposing through traffic has a green light — but only after the turning driver has yielded and determined there is a safe opening.
Message boards will be placed along Natoma Street to alert motorists to the change. The city is encouraging drivers to remain attentive as they become familiar with the new signals and to remember that a flashing yellow arrow does not give a driver the right of way. Oncoming vehicles, bicyclists and pedestrians must be allowed to pass before a left turn is made.
Not every new movement at the four intersections will begin operating Tuesday. Activation will be delayed for two left-turn movements because of conduit construction issues.
One is the new turn at Prison Road into the adjacent development. The other is one of the turns at Wales Drive near Folsom City Hall. The city is working to resolve the conduit issues and plans to activate those signals once the necessary work is completed.
The Sept. 8 activation represents the culmination of a pilot program that began taking shape after the Folsom City Council gave the proposal its approval. Construction on the Natoma Street locations began this summer, with crews adding a fourth signal section to accommodate the flashing yellow arrow.
The technology gives traffic engineers greater flexibility in managing left turns. Instead of operating exclusively with a protected left-turn phase, the signals can provide both protected and permissive opportunities depending on traffic conditions.
Under the four-section configuration, a steady red arrow means drivers must stop and wait. A steady yellow arrow alerts motorists that the signal is changing. A flashing yellow arrow permits a left turn after yielding to oncoming traffic, bicyclists and pedestrians, while a steady green arrow provides a protected left turn.
The flashing yellow phase is intended to reduce unnecessary waiting when sufficient gaps exist in opposing traffic, particularly during periods when traffic volumes are lighter. The system also allows traffic signal timing to be adjusted according to conditions and time of day.
When the program was considered by the City Council, city staff cited potential benefits that included reduced intersection delays, improved management of vehicle queues and less vehicle idling. Information presented by the city indicated protected-permissive left-turn operations can reduce vehicle emissions by approximately 9% to 12%.
Flashing yellow arrows are not new to the region. Roseville and Elk Grove have already installed them at multiple intersections, and the traffic-control method is used in communities throughout California and across the country.
“Many jurisdictions, including neighboring cities, have implemented FYAs, creating regional consistency for drivers,” Folsom Public Works Director Mark Rackovan shared in the city staff report presented when the program was considered by the council.
At the time, city staff evaluated a much broader group of Folsom intersections for their potential suitability for flashing yellow arrows. Preliminary evaluations identified 19 possible locations across the city, including intersections along Oak Avenue Parkway, Riley Street, Natoma Street, Sibley Street, Empire Ranch Road and East Bidwell Street.
Those evaluations considered several factors before an intersection could be viewed as an appropriate candidate. Among them were available sight distance, traffic speeds, the number of opposing lanes, traffic volumes and left-turn collision history. The criteria were designed to identify locations where permissive left turns could be introduced without compromising safety.
The Natoma Street intersections ultimately became the locations selected for Folsom’s initial pilot.
The four locations also presented an opportunity to evaluate the technology along the same corridor rather than introducing isolated signals throughout the city. Some of the Natoma Street intersections required upgrades to existing traffic signal equipment as part of the conversion.
The broader evaluation estimated that flashing yellow arrow installations could cost approximately $15,000 to $47,000 per intersection depending on existing equipment and the extent of improvements required. Costs can include new signal heads and hardware, controller and cabinet upgrades, installation labor, engineering and design work and contingency expenses.
The pilot was designed not simply as a traffic signal upgrade but as a test that could shape how Folsom handles left-turn movements elsewhere in the future.
Beginning with Tuesday’s activation, the Folsom Public Works Department will monitor how the new signals perform along Natoma Street. The city will use the results of the pilot program to help determine whether flashing yellow arrows should eventually be expanded to other intersections throughout Folsom.
For motorists, the most immediate change comes Tuesday: When the yellow arrow begins flashing, a left turn is permitted, but drivers must first yield to oncoming traffic, bicyclists and pedestrians and make the turn only when it is safe.
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