This project will increase capacity, improve traffic safety and relieve congestion on this stretch of U.S. 26. Once complete, there will be three lanes in each direction of U.S. 26, from Cornelius Pass Road into downtown Portland.

Construction began in November 2016 and will continue through the end of 2018. Learn more about construction and noise impacts at this online open house.

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Project Information

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Overview and Background

Learn how ODOT is working to add capacity to U.S. 26. 

Traffic Impacts

Work will impact traffic from November 2016 through December 2018. 

Noise Impacts

Residences and businesses adjacent to the project area may experience daytime and nighttime construction noise. 

Stay Safe, Stay Informed

Stay safe and keep informed about construction activities. 

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Overview and Background

ODOT is working to add capacity to U.S. 26.

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  • Project Elements

    Project Elements

  • U.S. 26 Widening

    U.S. 26 Widening

    Once complete, there will be three travel lanes in each direction from downtown Portland to Cornelius Pass Road. Most of the highway widening will occur in the highway median; highway shoulders will also be widened. Cable and concrete barriers will be added to the highway median.
  • Rock Creek Bridge Replacement

    Rock Creek Bridge Replacement

    Accelerated Bridge Construction (ABC) Technology will be used to replace the bridges over Rock Creek. This approach reduces onsite construction time by building bridge elements offsite. This has the advantage of reducing traffic impacts and reducing the overall duration of construction. When construction is completed, the trail below the bridge will be fully illuminated to ensure a comfortable experience for pathway users.
  • Cornelius Pass Interchange Improvements

    Cornelius Pass Interchange Improvements

    Cornelius Pass Road southbound will be widened approaching the interchange, including a dedicated right turn lane for the U.S. 26 westbound on-ramp. Westbound ramps will be reconfigured to improve connections for pedestrians and cyclists. An additional lane will be added to the to the U.S. 26 westbound off-ramp to Cornelius Pass Road southbound, and a signalized right turn onto southbound Cornelius Pass Road will be added.
  • Noise Walls

    Noise Walls

    Noise walls will be built on the north side of U.S. 26 in the Rock Creek neighborhood. There will be two walls – one on either side of Rock Creek.


The stretch of U.S. 26 between Cornelius Pass Road and 185th Avenue has reached its vehicle capacity. The population and employment in Washington County continues to grow, increasing the traffic demand on U.S. 26. Without improvements, congestion and related crashes are anticipated to increase.


This project is part of a phased approach to addressing congestion on U.S. 26. It follows earlier project work on U.S. 26 and is being coordinated with nearby roadway improvement projects. This effort continues a partnership between ODOT, the City of Hillsboro, and Washington County.

This project will:

You can learn more about these four project elements in the previous online open house (opens link in new window).

Traffic Impacts

Work will impact traffic from November 2016 through December 2018. Users should expect increased congestion, delays and noise in the project area for the next two years, however there will be no daytime lane closures of U.S. 26.

U.S. 26 Impacts

  • Nighttime lane and ramp closures on U.S. 26. Ramp closures will begin at 9 p.m. and lane closures will begin at 10 p.m.
  • Reduced shoulder access and traffic shifts on U.S. 26.
  • Work not requiring lane closures will take place during the day (such as building sound walls).
  • Nighttime lane closures on Cornelius Pass Road.

Rock Creek Trail Impacts

  • The Rock Creek Trail under U.S. 26 will be closed for two separate weekends and six separate nights — with a detour in place — as the new bridge is constructed.
  • There will be periodic flagging on the trail.
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Noise Impacts

Residences and businesses adjacent to the project area may experience daytime and nighttime construction noise.

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Comparing Noise Levels

  • Comparing Noise Levels

    Comparing Noise Levels

Pile Driving

There will be pile driving while building the new Rock Creek Bridge. Pile driving refers to the mechanical process of driving or repeatedly pounding piles (poles) into soil to provide foundation support for the new Rock Creek Bridge. The pile driving will take place during the day. The contractor is expected to complete all noisy work by 10 p.m., if possible.


A noise hotline is available 24-hours a day for reporting noise concerns. That number is 971-673-5239. ODOT staff will be available to answer immediate noise concerns during nighttime work by calling the noise hotline.

Noise Definitions

  • Noise - Unwanted sound which disturbs people or interferes with human activity.
  • Decibel (dB) - Logarithmic unit of sound measurement. (A difference of 10dB means that one noise is 10X louder; a difference of 20db means that one noise is 100X louder, etc.)
  • ‘A’ weighted decibel (dBA) - In acoustic measurements where the primary concern is the effect on humans, the sound readings are sometimes compensated by an “A” weighted filter. This accounts for people’s limited hearing response in the upper and lower frequencies.

Other noise related terms:

  • Leq noise level - Also known as equivalent sound level. The preferred method to describe sound levels that vary over time, used for most environmental noise measurements. Leq takes into account various noise levels throughout a given time period and averages them.
  • L10 noise level - This is the “A” weighted sound level that is exceeded 10 percent of the time. A useful descriptor of road noise because it correlates to the louder sound level people notice when close to busy roads and rural situations.

Stay Safe, Stay Informed

Thank you for your interest in the project. Stay safe and keep informed about construction activities using the resources below.

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  • Schedule


Stay Informed

  • Visit www.CornPass185.org to find current information, including detailed traffic impacts in a weekly construction update posted every Friday.
  • Learn how construction will affect traffic by visiting at www.TripCheck.com or by dialing 511.
  • Follow ODOT on Twitter and Facebook @OregonDOT
  • For more information contact, Lili Boicourt, ODOT Community Affairs, at 503-731-8247.


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About this site

This web site was developed by JLA Public Involvement and is not hosted by the Oregon Department of Transportation, though we adhere to the same accessibility guidelines. If you have any problems with the information on this page, please contact technical support, (503) 235-5881 for assistance.