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Road construction and maintenance

Road construction and maintenance

Traffic signals

Getting better performance out of our traffic signals is a high priority, both for Public Works and for the Board of County Commissioners. The Traffic Signal Optimization Program allows the county to improve traffic flow and make rapid signal adjustments in response to accidents, construction or everyday congestion.


For decades, most traffic signals were governed by a programmed cycle dictating how much time is allotted to red, green and, for some signals, left-turn movements. Magnetic detectors embedded in the pavement also allowed vehicles to “trigger” a cycle change and provided some ability to hold green lights for vehicles.

With new technology, the county is able to enhance those capabilities by adding video and radar detection. Modern signals can use this technology to detect oncoming vehicles and adjust signal timing more efficiently and safely for traffic flow.

The county’s goal is to manage traffic signals as an integrated network, not a collection of individual intersections. Someday, motorists could travel the length of the Padden Parkway-78th Street corridor and get a green light at every county-controlled intersection.


The county already has completed an upgrade of traffic signals on Northeast 134th-139th Street in Salmon Creek. The project involved 17 different intersections, including NE 20th Avenue/Highway 99 and NE 129th Street/Highway 99 intersections.

That signal optimization project is tied into additional signal, road and freeway work that is being done with the Salmon Creek Interchange Project. The completed allows the county to adjust signal operations and better manage traffic during construction, instead of simply defaulting to a programmed cycle for signal operations.

In the first three years of the program, approximately half of the traffic signals in Clark County have been upgraded. The rest of the traffic signals in the Clark County system are expected to be upgraded in 2014 and 2015 Most of the work has been paid for using federal grants.

Upcoming work

The next group of traffic signals to be upgraded on County roads are under contract, and are scheduled to be under construction in early 2014. These additional improvements include traffic signals on the following corridors:

• NE Highway 99, from the Ross complex to NE 117th Street.
• NE 78th Streets, from NW Ninth Avenue to to St. Johns Road.

Later in 2014, the remaining traffic signals in the Felida/Hazel Dell area, along with traffic signals in the Barberton are expected to be upgraded. Design work has begun to upgrade county traffic signals in the Sifton and Orchards area. The upgrades for the traffic signals in the Sifton and Orchards area are planned for 2015.

Flashing yellow arrows
A new type of signal is being installed and retrofitted to county traffic signals

Flashing yellow arrows allow drivers to turn turn left after yielding to oncoming traffic, pedestrians and cyclists. Drivers should not creep out into the intersection, but wait behind the white stop line until there is a sufficient gap in oncoming traffic and no pedestrians or cyclists.

Flashing yellow arrows can reduce congestion and prevent traffic from backing up at some intersections.

Report problems

If you see a malfunctioning traffic signal, please call our Customer Service lines at (360) 397-2446 or submit an online road maintenance request.


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