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Seattle/Bellevue Area Questions


Welcome to "Ask the Traffic Team," a Web page created to answer your everyday questions about traffic issues in WSDOT's Northwest Region.  You can find common questions sorted by subject in our Frequently Asked Questions archive.

If you'd like to learn more about our Seattle-area traffic camera page, you can check out the Seattle Traffic Questions page.

To submit your question, simply e-mail our Public Affairs office and provide as much detail as possible. You can typically expect a response with a week.


SR 9 signal
Dale from Lake Stevens wants to know why WSDOT removed the free right turn on green from the SR 9/Soper Hill Road intersection. Before recent construction, drivers headed east on Soper Hill could turn right onto southbound SR 9 near the truck scale. Now drivers can only turn on a green light or green arrow. Why?

North Bend cameras
Jack from North Bend wonders why WSDOT has no cameras between Issaquah and the I-90 summit. Can’t a camera be installed in North Bend?

I-90 ramp meter
Phil from Mercer Island wonders why the ramp meter from West Mercer Way to westbound I-90 cycles so slowly. Often it takes up to 10 seconds for the light to turn green. The Island Crest Way meter, on the other hand, cycles much faster. What’s going on?

ANSWERS

Q: Why do drivers at the SR 9/Soper Hill intersection have to wait for a green light or arrow to turn south on SR 9?
We installed the green right-turn arrow for the safety of drivers, truckers and pedestrians using the SR 9/Soper Hill Road intersection. Because the sight distance and setup of the intersection changed, we posted the no turn on red sign.

Prior to construction, the intersection never had a true “free” right turn. A “free” right turn is one where drivers can turn without having to stop or yield to other traffic – like on a freeway off-ramp. This intersection had a typical “right-turn-on-red” setup, where drivers could come to a complete stop at a red light, check for traffic, then turn right onto SR 9.

The intersection setup before construction was also a bit different. Southbound SR 9 had a left-turn lane, a through lane and a right-turn lane. The right turn lane was also used as an acceleration lane for trucks leaving the weight station and continued a short distance on the south side of the intersection. On Soper Hill Road, the stop bar for eastbound drivers was also fairly close to the intersection, giving them a good view of traffic on SR 9.

After construction, the location of the truck scale and truck acceleration lane moved west and are separated from SR 9 by barrier and curbing. In addition, southbound SR 9 now includes a second southbound through lane and separate right-turn-only lane, along with a left turn lane. Those changes moved the stop bar for eastbound drivers on Soper Hill Road back away from the intersection – potentially limiting their sight distance on SR 9. Even though the truck scale isn’t open often, drivers who pull forward to make a right turn on red can block the truck acceleration lane and the crosswalk at the SR 9/Soper Hill Road intersection. For those reasons, we posted the no right turn on red sign and added the green right-turn arrow.
*This question and answer came from Bill Sheets and his Street Smarts column in the Everett Herald.


Q: Can WSDOT install a camera along I-90 near North Bend?
Unfortunately, we have no plans to add cameras in the vicinity of North Bend at this time. In addition to the pole and camera equipment, new cameras also require power and a link to our traffic operations center in Shoreline – and that can be costly. Typically, our folks here at traffic operations will request that new cameras be added to major construction projects, such as a roadway widening project through that location. These projects are big enough to absorb the costs of new cameras, but there haven’t been any widening projects near North Bend and nothing is planned in the near future.


Q: Why does the West Mercer Way ramp meter work so slowly and the Island Crest Way meter work so quickly?
You have good timing, since we’re in the process of analyzing the meter rates for all ramp meters in our region. Looking at data from the past two months, we found that the Island Crest Way to I-90 ramp meter typically has a longer wait time per vehicle due to the higher ramp volumes than W Mercer Way does. Volumes on the W Mercer Way ramp to I-90 are a lot lower than Island Crest Way. That is why the ramp at Island Crest Way has two metered lanes, whereas W Mercer Way has only one metered lane.

The meter rates aren’t set to a specific time; they fluctuate depending on traffic conditions. Te rates are calculated using a logic system that takes into account real-time ramp volumes, traffic volumes on I-90, and the amount of traffic “downstream” from the ramp. These rates are calculated and updated every 20 seconds. When I-90 is heavily congested, the meter rate would be at the low end so that drivers would have to wait longer to enter the roadway. However, when the ramp volumes are high, the meter will speed up to put vehicles on the freeway at a faster rate to relieve the ramp backups.
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