We improved access to and from Interstate 5 at State Route 531 (172nd Street NE) by building a new two lane loop ramp, adding turn lanes and widening existing ramps.
In winter 2005, WSDOT and contractor Graham Construction finished building a new six-lane bridge south of Arlington.
Why did WSDOT improve this interchange?
More than 40,000 vehicles use the 172nd Street NE interchange (or Smokey Point Bridge) to access I-5 each day. Increased traffic had caused severe backups on and around the bridge during peak commute times and on weekends. Traffic was heaviest for drivers heading from westbound SR 531 to southbound I-5.
Between 2002 and 2006 the number of drivers turning left onto the on-ramp to southbound I-5 increased by nearly 15 percent. Although the new six-lane Smokey Point Bridge has alleviated much of that congestion, rebuilding the ramps at this interchange helps improve the flow of traffic to and from I-5.
The End Result
Drivers will now notice wider ramps and improved access to and from I-5 at SR 531.
- Realigned the ramps to and from I-5 to fit the wider, longer bridge.
- Added a loop ramp from westbound SR 531 to southbound I-5. The ramp has an HOV bypass lane and a metered general purpose lane.
- Widened both the northbound and southbound I-5 on- and off-ramps.
- Added right-turn lanes and traffic signals.
- Widened the existing eastbound SR 531 to southbound I-5 on-ramp to include an HOV bypass lane and a metered general purpose lane.
- Widened the existing northbound I-5 off-ramp to two lanes.
- Upgraded lighting, striping, signing, guardrail and fencing.
We also constructed a new park and pool lot off of SR 531 at 27th Avenue, with over 60 parking spaces. The old space was demolished to make way for the new improvements.
We brought these ramps up to current WSDOT safety standards. This project will help reduce the risk of accidents for vehicles traveling the I-5 corridor, as well as those entering and exiting the freeway at this interchange.
By widening and realigning the ramps we will improve traffic flow at the interchange of SR 531 and I-5.
| Protects Environment
We improved drainage and storage for highway stormwater runoff, which improves the water quality in the area.
Partnerships & Cooperation
On Jan. 12, 2009 we awarded the contract for this project to the most competitive bidder, Northwest Construction Inc. On March 2009 we began construction. On Nov. 13, 2009 we celebrated the early opening of the new and improved on- and off-ramps at the interchange. We also dedicated the SR 531 overpass in honor of Oliver "Punks" Smith, a longtime Arlington civic leader. We completed the project in July 2010.
This project was funded through the following fund sources:
- 2005 Gas Tax (Partnership Funding) - $22.75 million
- Other agency funds - $725,000
- Other funds provided by developer mitigation
- Total Funding Available From All Sources - $23.5 million
Note: the 2008 legislature allocated $33 million for this project, but WSDOT saved nearly $10 million when engineers reduced costs during project design and bids for the project were lower than the engineering estimated budget. The $10 million in cost savings will be reallocated to pay for other state transportation projects.
How can I get more information?
Project Engineer Amir Ahmadi
9029 El Capitan Way
Everett, WA 98208
WSDOT Communications Meghan Pembroke
15700 Dayton Avenue North
Seattle, WA 98133
Phone: (206) 440-4704
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