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Moving traffic with synchronized signals

Drivers on Aurora Avenue North already enjoy savings in time and fuel with newly-retimed signals.  Now others in the county will soon be seeing the benefits of synchronization. [enlarged view: 46 KB]

See the Eastside Journal editorial

The King County Traffic Engineering Section has been working on synchronizing signals on key arterials for several years.  King County Executive Ron Sims this week awarded grants totaling $400,000 to seven local jurisdictions to synchronize the traffic signals along nine regional traffic corridors. The funds will help traffic move faster on a combined 20 miles of roadways.

“For the cost of installing a signal with turn lanes at just one intersection, we are improving the flow of traffic for motorists throughout the County,” said Sims. “We are taking the next step in our Regional Arterial Network program by tackling traffic on our busiest corridors in the County - we are timing our traffic on those major arterials. By synchronizing signals we can reduce driving time, increase transit efficiency, save fuel and improve our air quality.”

Funding for the grants was made possible by voter approval last fall of the .2 percent sales tax that restored much of the funding for Metro Transit bus service. The grants reimburse the cities for retiming and testing traffic signals so they work together to give the green light to flows of traffic.  The grants are to: 

• Burien and unincorporated King County: 17 signals on Ambaum Blvd. and 16th Ave. SW, from SW 100th St. to SW 153rd St., $85,000
• Federal Way: 11 signals on State Route 99, from 16th Ave. S. to S. 288th St., $55,000
• Issaquah: four signals on SE 56th, from East Lake Sammamish to 11th Ave. NW, $20,000
• Kent: five signals on State Route 99, from S. 240th St. to S. 272nd St., $25,000; and 11 signals on West Valley Highway, from Kent-Des Moines Road to Todd Blvd., $55,000
• Kirkland: six signals on NE 85th St. and 124th Ave., from 114th Ave. NE to 132nd Ave. NE, $30,000
• Kirkland and unincorporated King County: five signals on NE 132nd St., from 116th Way to 132nd Ave. SE, $25,000
• Renton: eight signals on Grady Way, from Oakesdale Ave. SW to Main Street, $40,000
• Seattle: 13 signals on Elliott Ave. and 15th Ave. W., from Denny Way to Armour Street, $65,000.

The grants represent the first phase of an overall $1.5 million grant program, with more grants to be awarded over the next three years to get traffic moving more quickly on key regional arterials.

The grants build upon work done by King County on other signal synchronization projects in 1999 and 2000.  Based on "before and after" studies on those corridors, traffic engineers found that the synchronized signals reduced travel time by anywhere from 5 to 30 percent. The projects implemented in 1999 and 2000 include:

• SE Petrovitsky Road from 128th Avenue SE to 151st Avenue SE
• Aurora Avenue N. from N. 155th Street to 200th Street, with the City of Shoreline
• 15th Avenue NE from NE 175 Street to NE Perkins Way, with the City of Shoreline
• SE 208th Street from 116th Avenue SE to 132nd Avenue SE
• Coal Creek Parkway SE from SE 69th Way/SE 72nd Place to SE 91st Street, with the City of Newcastle

Synchronized traffic signals are also part of new Intelligent Transportation Systems (ITS) that King County is building to use technology to reduce congestion and move vehicles and buses faster and more reliably along two major corridors:

• The NE 124th Street ITS Project will have synchronized signals, transit signal priority, traffic cameras, and advance traveler information available through the Internet. The corridor runs from 100th Avenue NE to State Route 202, with construction starting this fall through the spring of 2002. The project is a partnership with the city of Kirkland and the Washington State Department of Transportation.

• The TransValley/Petrovitsky Road ITS Project will have synchronized signals, transit signal priority, traffic cameras, advance traveler information, and variable message signs. The corridor runs from Southcenter Parkway to Southeast 184 Street, with studies being done this year for construction in 2002 and 2003. The project is a partnership with the Washingon State DOT and the cities of Tukwila, Renton and Kent.

The signal synchronization program supports the county’s Regional Arterial Network of key transportation corridors, and enhances the speed and reliability of the Metro bus system. Executive Sims noted that synchronized signals are the kind of arterial improvements envisioned by regional funding packages now pending in the State Legislature.

"People in our region make several hundred thousand trips on arterial streets each day" said Executive Sims. "While improved capacity on state highways is important, the Legislature should also include funding for arterial streets. We’ve proven that modest investments in signals can have big pay-offs."

Related links

"A smart way to get traffic moving again," editorial, Eastside Journal, April 20, 2001
"Kirkland, Issaquah get funding to synchronize traffic signals," Eastside Journal, April 19, 2001
"County goal: Traffic in sync," Seattle Times, April 18, 2001
"County grants will help smooth traffic flow," South County Journal, April 18, 2001
"Transit Signal Priority shown to cut travel time,
work to synchronize signals at 80 intersections planned county-wide," news release, Feb. 12, 2001
"Metro Transit measure passes; Sims outlines implementation plan," news release, Nov. 8, 2000
"Sims outlines transportation package," news release, Sept. 21, 2000

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