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I-405 - NE 116th St Interchange and Street Improvement Project - Complete March 2013

Project Status - Complete
Map showing project limits for the NE 116th interchange project  
This map shows the project limits for the NE 116th interchange project.

The new SPUI at NE 116th Street

One of the central improvements is a new interchange design that maximizes traffic flow in a congested area. For more photos showing construction progress, visit our Flickr page.

New pedestrian features beneath I-405 at 116th Street

Pedestrians now have better and safer access at the NE 116th Street underpass, thanks to new lighting, wider sidewalks, and seating.

Overview

WSDOT undertook this project to improve traffic flow at the 116th Street interchange in Kirkland, particularly during the congested morning and afternoon commute times. This work complemented the I-405 Kirkland Stage 1 project completed in November 2007.

The project scope included:

  • Adding lanes to NE 116th Street near the interchange with I-405.
  • Improving signalization at the NE 116th Street and 120th Avenue NE intersections.
  • Building a sidewalk for pedestrians and a bike lane in each direction of NE 116th Street under I-405.
  • Rebuilding the structure over the port-owned rail line.
  • Transforming the off-ramp from northbound I-405 and the on-ramp to southbound I-405 at NE 116th Street from a traditional half-diamond interchange configuration to a half Single Point Urban Interchange (SPUI).

What is a SPUI?
With the new SPUI (pronounced "spooey") design, the on- and off-ramps converge at a single location controlled by one set of traffic signals at the center of the interchange. The signal in this case is located on the underside of the I-405 overpass.

The SPUI design increases the number of vehicles that can clear the interchange each time the light turns green for a particular stream of traffic.

More resources

  • Check out our project folio (PDF) for more details about the project and how a SPUI works.
  • Watch our YouTube video to learn more about your new, more efficient interchange.
  • View photos of the construction process on our Flickr page.

How You Benefit
Cross GlyphImproves Safety
This project improves safety for drivers, pedestrians, and bicyclists. We reconfigured the traffic signals at the intersection of NE 116th Street and 120th Avenue NE. The project also constructed a new sidewalk on the south side of NE 116th and bike lanes in each direction of the NE 116th Street under I-405.
Car GlyphRelieves Congestion
The project's improvements add capacity and increase efficiency for vehicles exiting and entering I-405. By changing this interchange from a traditional one to a more efficient half Single Point Urban Interchange, or SPUI, we are able to maximize traffic flow in this notoriously congested area. The new lanes on the NE 116th railroad crossing reduce congestion and improve access to neighborhoods and businesses.
Leaf Glyph Protects Environment
WSDOT's I-405 Corridor Program team is designing the project to avoid and minimize impacts to the environment. A new stormwater pond and drainage vaults will improve water quality.

Partnerships & Cooperation
WSDOT worked closely with the City of Kirkland to bring these improvements to the area. We also collaborated with the Cascade Bicycle Club and Bicycle Alliance of Washington do design the bike lane configuration for the project.

Funding

Financial Data for PIN 840561D
Funding Source Amount ($ in thousands)
2003 Gas Tax (Nickel Funding) $109,521
2005 Gas Tax (TPA) $0
Pre-Existing Funds (PEF) $1,093
Total $110,614

Contact Us
Steve Peer
I-405 Corridor Program
600 108th Avenue NE
Suite 405
Bellevue, WA 98004
425-456-8624

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