Monday, March 2, 2015

Coming soon: Coal Creek Parkway ramp meter to better manage I-405 traffic

By Justin Fujioka

A relatively quick, low-cost project is underway to install a
ramp meter from Coal Creek Parkway to southbound I-405.
The Coal Creek Parkway on-ramp to southbound I-405 is finally getting some love, and that’s great news for drivers between Bellevue and Renton. This busy ramp has been sitting single on the sidelines as the only one in the area without a ramp meter. Until now.

A relatively quick, low-cost project is underway to install a meter on the ramp and improve traffic flow along a busy corridor that’s congested almost every afternoon. There was no space for a ramp meter there because of a bus stop along the on-ramp. Well, the bus stop was recently moved to the next off-ramp (Lake Washington Boulevard), where a park-and-ride was built.

A bus stop along the on-ramp was removed recently,
making space for a ramp meter to be installed.
You may be wondering how adding a ramp meter – basically a traffic light – will improve traffic flow. Think of it like this: You’re at a wedding and eager to get to the buffet line at the reception. If everyone gets up from their table at the same time, the buffet will be crowded with everyone struggling to get to the salmon or chicken. But if the tables are dismissed one by one, the buffet line will move more smoothly and everyone wins. That’s basically what a ramp meter does. It dismisses each table, or car, one by one, providing an even pace for vehicles to enter the highway and promote easier merging and better traffic flow.

Like all metered on-ramps, we will monitor the need for activation daily while keeping an eye on the nearby
The Coal Creek Parkway on-ramp to southbound I-405 is
currently the only one in the Bellevue area
without a ramp meter.
surface streets. The ramp meter will only activate when traffic on southbound I-405 dips below the posted speed limit.

The $220,000 project will require lane and ramp closures through early April, when the project enters its honeymoon phase. Until then, drivers should prepare for a full closure of the ramp each weeknight during the week of March 9. There will also be some daytime lane closures on the ramp. For updates on the latest lane and ramp closures, visit our I-405 Construction Update Report.


Anonymous said...

Traffic on southbound Lake Washington Blvd often is backed up by a mile or more during the PM peak at this ramp. I'm curious if that will improve or degrade with the metering. Very limited storage for vehicles making a right turn onto the ramp, which will affect thru traffic.

WSDOT said...

After construction is complete, the City of Bellevue and WSDOT will collect data and explore strategies to manage traffic before the ramp meters are turned on. The city will also be adjusting signal timing on surface roads, as needed, to work together with the freeway system.

Dr V said...

I've often wondered if S-curve traffic flow on 405 could be further smoothed by adding over-lane dynamic speed signs. Possibility??

D... said...

Oh please god no. Those variable speed signs are literally the stupidest most inane useless things Ive seen. Nobody pays any attention to them, theyre just a damned hassle that causes a few people who drive too slow and not with the flow of traffic to drive even slower, and they are just a general confusion to just about everybody. They turn those things on the 520 before the 405 exits and just mess up the flow of traffic worse than it was before.

annonymous said...

The Coal Creek Ramp seems functional, but the control lights have not yet been turned on. When does WSDOT plan to turn the lights on this ramp on?

WSDOT said...

WSDOT is currently working with the city to modify the signal on Coal Creek Parkway to make sure it is in conjunction with the ramp meter operation. When that is worked out, the control lights will be turned on.

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