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About The Bridge

A Tale of Two Bridges

The Interstate Bridge is actually made up of two side-by-side bridges. The northbound bridge was built in 1917 and the southbound bridge in 1958.

The 1917 Bridge: Shift from Ferry to Bridge Travel

In 1905, the first world’s fair to be held in the Pacific Northwest opened in Portland, Oregon. The event was a promotional boon to the Vancouver/Portland area but caused a massive traffic jam at the Columbia River steam ferry, one of the few passageways between the two cities. This sparked widespread demand for a bridge between the two states. In 1914, with a great deal of bi-state local support, the Washington and Oregon state legislatures approved the sale of bonds to fund such a bridge. 

The new bridge opened in 1917 amid much fanfare. It cost travelers 5 cents to cross. There were only two lanes of traffic, one in each direction.  A streetcar shared the roadway with cars, most of them Model T Fords. Because the bridge was heavily used, the original bond was paid off within 12 years and tolls removed.

The 1958 Bridge: The Era of the Automobile

The end of the Vancouver and Portland streetcar service in the 1940s and increased travel on the bridge prompted Oregon and Washington to look into increasing the capacity of the bridge. Traffic rates had skyrocketed and it was time to look for solutions. A dramatic increase in marine traffic also required more bridge lifts, which made traffic problems even worse.

In 1953, the Oregon and Washington state legislatures authorized the sale of bonds to design and build a second bridge. Construction of a second parallel drawbridge was completed in 1958. Tollbooths were installed in 1960 after remodeling work on the 1917 span had been completed. To pay off the construction bond, tolls of 20 cents for cars, 40 cents for light trucks and 60 cents for heavy trucks and buses were collected until 1966.

Today’s Interstate Bridge and Plans for the Future

The Interstate Bridge has served us well for more than 90 years, but it is time to replace the two structures to best meet the next century’s growing travel needs across the Columbia River.

Today, the Interstate Bridge carries 135,000 vehicles per day. Because congestion is so heavy in the morning and evening commute hours, bridge lifts for river traffic have been restricted, but not prohibited, during the weekday rush hour.

The bridges were built on timber pilings, which still support them today. The pilings are driven approximately 70 feet below the river bottom. Recent geotechnical studies have shown that the sandy soil under the bridges will likely liquefy to a depth of 75 feet during a significant earthquake. This could cause severe damage to the bridges.

A replacement bridge will be designed to address future traffic demand, eliminate the need for bridge lifts and meet current seismic standards.

There are several issues to consider for a replacement I-5 bridge:

• Traffic and transit operations and safety
• Navigation operations and safety
• Community and economic effects
• Natural environment effects
• Bridge aesthetics and design
• Number of lanes
• Design of pedestrian and bicycle facilities
• Mitigation plan
• Construction financing