Successfully Inspecting, Assessing and Repairing a Damaged Truss Bridge in 24 Days

• Rapid emergency response to inspect and partially reopen bridge in three days
• Fast-track structural repair design in just 10 days
• Engineered innovative temporary repair bracing for a 100-year-old bridge lift span
• 24/7 construction support to expedite bridge reopening

On June 27, 2024, an overheight truck struck the century-old Oregon Hood River-White Salmon Interstate Bridge. The impact damaged portal braces within the towers and lift span, forcing the vital connection between Oregon and Washington to close to commuter, freight and marine traffic. The bridge enables 4.5 million crossings each year, and its closure required drivers to take a 50-mile detour to cross the Columbia River.

With tens of thousands of daily users impacted daily by the bridge closure, the Port of Hood River turned to HDR to lead the emergency response, beginning with inspecting and assessing the bridge. As project manager, our role quickly expanded to include leading the final repair design on a fast-tracked, 24-day schedule to safely reopen the bridge. With similarly aged infrastructure across the U.S., this project is an example of how to rapidly close, assess, repair and reopen critical truss bridges following a strike incident.

Responding to an Emergency

Immediately after the strike, HDR deployed an inspection team to evaluate the structural damage to the bridge, discovering damage to six overhead portal braces. Within hours, the team coordinated a virtual meeting from the site with engineers throughout the firm to convey the extent of damage and begin structural assessment work. This included examining as-built drawings, inspection records, photos and load ratings to understand the original design and subsequent modifications.

To reduce the impact of the bridge closure, our engineers conducted around-the-clock structural evaluations over the next three days, balancing reasonable, conservative assumptions with necessary refinements. On June 30, following senior staff review, HDR completed a structural assessment and recommended that the Port of Hood River reopen the bridge to passenger vehicles only. HDR presented the findings during a live-streamed emergency meeting, providing the public with timely project updates. The meeting and the bridge’s partial reopening that same day proved to be a critical turning point in the emergency response.

Designing Complex Repair

Recognizing the significance of this bridge to the community and traveling public, and with truck and marine traffic still restricted, the team accelerated the design of structural repairs. Working through the July Fourth holiday, we delivered the Port of Hood River a final stamped repair design on Sunday, July 7, 2024, just 10 days after the vehicle strike.

A key challenge for designers was the dozens of modifications the bridge had undergone over its 100-year lifespan, including a transition from a fixed span to a vertical lift bridge in 1937. The strike damaged both the lift span and tower portal bracings. To support the design, our team built analysis models using 1920s as‑constructed plans to confirm loads and member forces. Three portal frames required individual analysis. Engineers developed temporary bracing by modifying the lifting span’s locking shoes — which support the bridge when raised — to instead stabilize it while closed for repairs. Replacement gusset plates were also designed with specific geometry to help construction crews more easily align work points, member ends and bolt locations during evening repairs.

Avoiding Further Delays

Quickly advancing the emergency bridge repair required completing several project steps at the same time, rather than one after another. Because of the long lead time to procure steel for structural repairs, our team developed an advanced material order based on preliminary engineering and engineering judgment before the final design was completed. This approach prevented schedule delays.

Repairs were completed over the next two weeks during overnight bridge closures. Throughout construction, the Port of Hood River and HDR team provided continuous 24-hour project coverage, supporting construction oversight during nighttime shifts, reviewing construction submittals, responding to contractors’ requests for information (RFIs) and planning for the next night’s work during daytime hours.

The Hood River Bridge fully reopened to all traffic on July 20, 2024, just over three weeks after the initial emergency response.