We will install meters at eight on-ramps to north and southbound I-5 between Tukwila and Federal Way.
- S. 188th Street
- S. 200th Street
- SR 516
- S. 272nd Street
Additionally, crews will restripe 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.
Additionally, 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.
Why is WSDOT
installing on-ramp meters in both directions of I-5 between Tukwila and Federal Way?
Ramp meters are an invaluable traffic management tool to help decrease travel times and reduce collisions.
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.
The project will cost about $1.4 million. The cost includes more than just the ramp meter signals. Crews will also rebuild the shoulders on the S. 188th Street ramps. By making these ramp shoulders stronger and better able to withstand traffic, the ramps will be restriped to accommodate two lanes of traffic. WSDOT will also install traffic detection loops on the interstate and ramps, repaint the ramps, install flashing amber advance warning signals and add signs.
The End Result
When the project is complete in June 2013, there will be meters on 11 ramps between S. 320th Street in Federal Way and S. 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.
- Safety: Studies have shown that ramp meters can reduce collisions system-wide by as much as 30%
- Congestion-relief: Ramp meters are a proven and cost-effective method of reducing congestion by allowing cars to enter a highway in controlled intervals, decreasing disruption to traffic on the freeway.
What is the project timeline?
In 2009, the Washington State Legislature identified ramp meters as congestion-relief project for this area and authorized project funding for it.
August 2011: Project design.
April 2012: Design completed.
June 2012: Advertised the project for contractors.
July 2012: Identify contractors.
August 2012: Crews begin construction by installing new traffic data and detection loops on the ramps. In the fall of 2012, we expect construction will begin on repaving and restriping the S. 188th Street ramps. Over the the next ten months, crews will construct concrete foundations, install poles, traffic signals, new signs and pavement markings.
June 2013: Complete construction and activate new ramp meters.
Funding for this $1,435,000 project came from pre-existing funds allocated by the Legislature.
How can I get more information?
WSDOT Traffic Engineer
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