The Oregon and Washington departments of transportation have drafted recommendations to scale back plans for a replacement Columbia River Crossing bridge and save $650 million on what had been estimated as a $3.1-billion to $4.2-billion project.
Much of the savings comes from shrinking the number of lanes to 10 from 12, eliminating two ramps and reusing the existing highway bridges over North Portland Harbor. “The bridge could be reconfigured to accommodate 12 lanes in the future,” says Carley Francis, Columbia River Crossing spokesperson.
The project, which originally called for construction to begin in early 2010, has been put off to 2012 at the earliest because the agencies still need to find funding for the new $2.6-billion to $3.6-billion project before beginning property acquisition and engineering work.
Construction would take from five to seven years.
A related proposal to eliminate elevated structures over Hayden Island and lower the profile of the interstate resulted in protests, and the departments are looking at ways to preserve more existing buildings while avoiding the cost of building on piers.
The design had to take into consideration a number of constraints, including a height requirement that was below the airspace of two airports but above the marine traffic height requirements while being sensitive to environmental concerns.
Plans call for a “signature” composite segmental box girder bridge designed by Tallahassee, Fla.-based Touchstone Architecture. No bridges of this type exist in the United States, but France’s Boulonnais Viaduct and Japan’s Kinokawa Viaduct are based on similar designs without utilizing the space below the deck the way the proposed Columbia River Bridge would do.
Francis says the design was chosen because it eliminates the need for a third bridge to carry light-rail and pedestrian/bicycle traffic while reducing the number of piers in the water and narrowing the river footprint. It also efficiently uses resources by utilizing a lower deck.
The 5-mi mile portion of Interstate 5 will include light-rail, interchange and pedestrian/bicycle improvements. The lead engineering company is David Evans and Associates Inc. of Portland.