New Interstate Bridge planners unveil 6 potential designs, from ‘finback’ to a familiar lift span

Planners for a new Interstate 5 bridge on Thursday introduced six possible designs for the proposed Columbia River span.

While key details are still uncertain — including when it might be built and how the $7.5 billion construction project would be funded —the new renderings show for the first time what the bridge could look like and how it would affect the skyline of the surrounding cities.

The six proposals are:

Extradose: A single-level bridge with low towers and cables that don’t protrude into the air space of Portland International Airport or Pearson Airfield.

Finback: A close relative of extradose bridge with its cables replaced by “fins” that contain cables within a concrete housing. Towers also don’t protrude into the airspace.

Concrete: A single-level bridge similar to Interstate 205′s Glenn Jackson Bridge that uses concrete with structural supports for the wider spaces between piers.

Steel Girder: Similar in same shape to the concrete bridge but with a structure made of steel, which is lighter.

Truss: A two-level structure, with highway on top and public transit and bike/pedestrian lanes underneath. No intrusion into airspace. Narrower than single-level bridge. The design is similar to the shelved Columbia River Crossing proposal.

Movable: A bridge with a lift deck, much like the two current spans that make up the current Interstate Bridge, to allow vessels to pass below. Mechanical parts would be housed within large towers. Crews would have to dredge the river channel to make it deeper, because the lift would not be at the current deepest part of the river.

The renderings show what the bridge would look like from east and west of the bridge in Vancouver and Hayden Island, but don’t show the how each would look from a street-level view on either side of the river. The renderings do show a possible view from the Hayden Island shared-use path, east of the bridge. It also wasn’t immediately clear how each design would affect the cost of the project. Greg Johnson, director of the Interstate Bridge Replacement Program, told a steering committee made up of local government and transportation officials that his design team would develop detailed renderings.

The Interstate Bridge team must build a bridge that allows ships to pass under it, as well as products manufactured by several local companies located upstream. Absent a drawbridge or movable span, the bridge must be at least 178 feet high to clear those vessels, according to the U.S. Coast Guard, which must sign off.

Despite the unveiling, the new Interstate Bridge is far from a done deal.

Oregon lawmakers have failed to pass a bill that would have borrowed $1 billion to help pay for the bridge. The state legislature could still allocate that money as part of a broader budget bill. Federal funding that will pay the bulk of the cost hasn’t been secured.

And the bridge plan still must submit an environmental impact statement for public review and approval by the federal government.

Chris Regan, the environmental manager for the bridge replacement program, told local officials he expected the environmental impact statement to be ready for review in late 2023, and after a 60-day public comment period, it could be submitted to the federal government.

Vancouver Mayor Anne McEnerny-Ogle stopped him.

“Sixty days isn’t going to cut it for the city of Vancouver,” she said, noting that the public comment period would fall in the middle of the holidays and limit community engagement. “We’re going to need 90 days.”

—Jayati Ramakrishnan; jramakrishnan@oregonian.com