Drivers in Kent and Tukwila should plan ahead for multiple lane closures on northbound Interstate 5 every night from Monday, Oct. 1 through Thursday, Oct. 4 near State Route 516 and South 188th Street.

Additionally, the on-ramps from South 188th Street to northbound and southbound I-5 also will close each night, according to a state Department of Transportation media release.

During the closures, crews will install traffic detection loops under the freeway lanes and rebuild the shoulders of the ramps.

The traffic detection loops and ramp shoulder work is part of the I-5 Tukwila to Federal Way ramp meters project, at a cost of $1.4 million. The state DOT will install ramp meters at four interchanges in south King County where traffic routinely slows to a crawl during the morning and afternoon commutes.

On Monday, Oct. 1 and Tuesday, Oct. 2, crews will close the three left lanes on I-5. The first northbound lane will close at 8 p.m., the second at 10 p.m. and the third at 11:59 p.m. On Wednesday, Oct. 3 and Thursday, Oct. 4, the two right lanes will close with the first lane closing at 8 p.m. and the second at 10 p.m. All lanes and the ramps will reopen daily by 5 a.m.

The state DOT plans to install meters at eight on-ramps to north and southbound I-5 between Tukwila and Federal Way at:

• South 188th Street

• South 200th Street

• State Route 516, also known as Kent Des Moines Road

• South 272nd Street

Additionally, crews will re-stripe the north and southbound ramps from S. 188th Street in order to accommodate two lanes of metered traffic. Currently, both ramps are one lane. The number of lanes on the other ramps will not change.

The S. 200th Street/Military Road ramp to northbound I-5 will not have a meter because the ramp is not long enough to provide storage room for cars waiting at a meter plus enough distance for a driver to match the speed of traffic on the mainline while trying to merge.

There are three ramp meters already in place at S. 320th Street. These meters will be used in coordination with the new meters to manage the traffic in the Federal Way to Tukwila corridor.

Ramp meters are an invaluable traffic management tool to help decrease travel times and reduce collisions, according to DOT officials.

The speed of traffic on I-5 in South King County has steadily dropped over the years.

Currently the average speed for northbound traffic during the morning commute is 37 mph. During the southbound evening commute, it’s 40 mph.

When traffic signals at interchanges near the on-ramps turn green, a rush of vehicles flood onto the interstate, slowing traffic already on the highway. Adding ramp meters will control the number of vehicles entering I-5 during peak commute times. The interstate can more easily absorb a single car at a time than a dozen of them at once.

Ramp meters help improve commutes by reducing congestion and creating a more consistent traffic flow.

When the project is complete in June 2013, there will be meters on 11 ramps between South 320th Street in Federal Way and South 188th Street in Tukwila.

Drivers will notice improved traffic flow.

Drivers will most likely see the ramp meters active between 6 and 8 a.m. for northbound traffic and 3:30 to 5:30 p.m. for southbound traffic.

For more information on closures in King County, visit www.wsdot.wa.gov/Northwest/King/Construction/

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