New Oregon-Washington I-5 Bridge Replacement Cost Estimate Swells to $14.4B

Plans to replace the five-mile bridge connecting Portland, Oregon, and Vancouver, Washington, on Interstate 5 are now expected to cost over $14 billion.

A new estimate published by the Interstate Bridge Replacement Program allotted $7.8 billion for the base cost of the new, fixed-span bridge’s construction with no complications, $4.2 billion for the risk of changes to cost and schedule, and $2.4 billion for the impact of inflation. The formal range of the estimate is $13.5 billion and $15.2 billion, but the program said there is a 70% chance the total cost will be $14.4 billion or lower.

New influences on this estimate, according to the program, include inflation driving up costs — Washington DOT says construction costs have risen 58% since 2022 — and market conditions creating higher bids.

This new estimate includes the following:

• Replacement bridges over the Columbia River and replacement of the North Portland Harbor Bridge
• Three through lanes and one auxiliary lane southbound and northbound
• Extension of light rail from Portland to Vancouver with the addition of three new station locations
• Rebuilt interchanges at Marine Drive, Hayden Island, SR 14, Mill Plain Boulevard, Fourth Plain Boulevard and SR 500
• A bridge for local traffic connecting Hayden Island to Marine Drive
• Improvements for people who walk, bike and roll

The project’s scheduled year of completion has been pushed from 2034 to 2045, driven by a two-year delay in the federal environmental process.

The existing interstate bridge sees over 143,000 vehicles per day and was built 109 years ago, putting it at notable risk of collapse from earthquakes. The EPA specifically points to the use of timber bridge piles in its original construction. 

“This collapse potential is due to the fact that hundreds of timber bridge support piles sit within loose sand that can liquefy during an earthquake,” the environmental impact statement says.

With $5.5 billion in funding already committed, work on replacing the Columbia River Bridge, building bridge connections to Interstate 5, extending the light rail to Waterfront Station, and removing the existing bridge will move forward as a “core set” of projects. Those projects are estimated to cost $7.65 billion.

Ongoing administrative work includes efforts to obtain an Amended Record of Distribution in 2026 to provide federal approval for the project. If successful, this would allow for the contractor hiring process to begin this year and for construction to begin in 2028.