King county increases Traffic Light Coordination

Suburbs getting traffic signals synchronized to ease the squeeze

Wednesday, February 20, 2002

By LARRY LANGE
SEATTLE POST-INTELLIGENCER REPORTER

During morning and afternoon commuting peaks, it becomes almost impossible to get into or out of the parking lot at Issaquah's Front Street Market.

Cars jam the street all the way from Interstate 90 to the Issaquah-Hobart Road as commuters and school buses vie for space on the main street in the city's historic district.

So even though synchronizing traffic lights may be only a temporary answer, market manager Lori Steendahl was glad to hear it will be done on Front Street near the store.

"It couldn't hurt," Steendahl said yesterday after King County announced $415,000 in light-synchronization work countywide. Speaking of Front Street, Steendahl said, "I don't know why they haven't tried that yet."

County Executive Ron Sims announced the latest batch of traffic-light synchronization work yesterday, the second year the county has conducted the work. Financed with money from a 0.2 percent sales-tax boost approved by voters in 2000, the work is scheduled to continue for two more years.

This year's work includes synchronizing five lights on Issaquah's Front Street, to improve traffic flow there at an estimated cost of $25,000 for five lights. But the list of nine projects range includes the coordination of 29 traffic lights on two sections of Seattle's Rainier Avenue between I-90 and 57th Avenue South.

The projects cover lights on some of the region's busiest roads. Not everyone has noticed a difference in traffic flow where the lights have been synchronized, but officials said many drivers have and seem pleased with it.
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Officials haven't yet estimated the time savings for the new projects. In Seattle, coordination of 20 lights on Aurora Avenue last year cut typical driving time 20 percent between Green Lake and North 145th Street, city transportation spokesman Michael Graubard said.

Savings can be achieved both in travel time and changes in speed, and some of the biggest improvements come in suburban areas, far away from the jammed streets of Seattle. Last year, synchronizing 11 signals on the West Valley Highway in Kent cut rush-hour driving time on the 3.5-mile stretch from more than 15 minutes to just under 11. Speed increased from 14 mph to 22.

Some of the savings are small but look bigger when the length of the congested roadway is considered. Speeds on a stretch of Northeast 85th Street in Kirkland increased 3 mph during rush hour after the county program synchronized five lights between 114th and 132nd avenues. It's only a one-mile stretch, but the change means speeds are one-third faster.

Some may not notice a difference. Representatives of three South King County businesses that use the West Valley Highway said their drivers hadn't mentioned any improvement in traffic speeds. Doug Kushan of City Beverage in Kent said many of his company's drivers start at 3:30 a.m. "so they miss a lot" of rush-hour traffic.

In Seattle, however, "people are noticing the difference, and they've been appreciating it and they're telling us," Graubard said. In addition to readjusting the Rainier Avenue lights, the city plans to spend $185,000 of its own money synchronizing 37 other signals -- 20 on Lake City Way, 12 on California Avenue Southwest and five on Northeast 145th Street, as part of a program of changes to be completed by April.

The fixes are just temporary. Traffic experts say traffic signals need to be recalibrated every three to five years to reflect changes in traffic patterns. That's what the city will be doing on the two sections of Rainier Avenue, where lights were last adjusted in 1998.