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Tuesday, November 28, 2023
Nov. 28, 2023

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Why alternative Interstate 5 Bridge replacement ideas won’t work

No shortage of ideas to fix an old span, but official says none meet the project’s requirements

By , Columbian staff writer
3 Photos
Illustration of the Interstate 5 Bridge with a tunnel.
Illustration of the Interstate 5 Bridge with a tunnel. (Bunk Hess/The Columbian) Photo Gallery

Nearly everyone agrees the Interstate 5 Bridge is not serving the region well.

It would be catastrophically damaged in a big earthquake, it lacks breakdown and auxiliary lanes, it is not safe for pedestrians or cyclists and freeway congestion is terrible — heaven forbid you’re traveling north after 3 p.m.

What people can’t agree on is what should replace it.

In addition to the options being considered by the Interstate Bridge Replacement program, and the Columbia River Crossing program before it, there has been a steady drumbeat of alternative replacements for the I-5 Bridge other than the program’s preferred fixed-span bridge with 116 feet of river clearance.

Should it be a tunnel? Should it have a moveable span? Why not a third bridge? Why does the current I-5 Bridge even need to be torn down?

Interstate Bridge program Administrator Greg Johnson doesn’t consider the alternative ideas bad, but he said none of them meet the program’s purpose and need to address seismic vulnerability, bike and pedestrian paths, public transportation, safety, freight movement and congestion.

Alternative approaches, including a tunnel, bascule bridge, third or supplemental bridge and even the “common sense alternative” do not meet the program’s criteria, Johnson said.

Some supporters of shot-down alternatives argue their preferred options better meet the program’s purpose and need — especially after the Coast Guard’s preliminary ruling stating that a replacement bridge must have at least 178 feet of river clearance.

“We’re having conversations with our federal partners and with the Coast Guard and trying to explain why we think a 116-foot fixed bridge is the right, appropriate way to move forward,” Johnson said.

Here are several alternative bridge replacements — and why Johnson thinks they’re not the best answer to the region’s transportation needs.

Immersed tube tunnel

One of the most vocal Interstate Bridge Replacement critics, Bob Ortblad, contends that an immersed tube tunnel is the best solution.

Ortblad, a retired civil engineer and a self-described “historian of 200 years of infrastructure” regularly comments at public meetings, voicing his dissatisfaction with the program’s direction and its lack of consideration of an immersed tube tunnel.

An immersed tube tunnel is an underwater tunnel composed of segments floated to the site, sunk and then linked together. No drilling down to bedrock is required, he said, and they are buoyant, making them seismically resilient.

Johnson agrees that an immersed tube tunnel is a clever idea, but he says it’s not a practical solution.

“It would solve a lot of things,” Johnson said. “We wouldn’t be at odds with the Coast Guard or the Federal Aviation Administration with a tunnel, but it creates so many other problems. It’s not feasible to do, and it doesn’t meet purpose and need.”

Ortblad argues that although a tunnel may cost more than a bridge, it will be cheaper overall because it can meet existing infrastructure; with a bridge, interchanges will need to be rebuilt.

Johnson disputes this, saying that tunnel cost estimates run roughly two times higher than the cost of a bridge even before factoring in highway, interchange or high-capacity transit improvements that would be necessary.

“You can’t get up to grade and go over (the BNSF Railway line), so you would have to go under, and therefore you’re going to miss SR-14 unless you do some weird loops that would destroy half of Fort Vancouver,” Johnson said.

Ortblad worries that a proposed nearly 4 percent grade on a high bridge, whether at 178 feet or 116 feet, is going to be dangerous, especially for truckers, because of the wet climate and potential for black ice.

“I contend this bridge is going to be a killer,” Ortblad said. “It’s going to be really dangerous.”

A tunnel, on the other hand, is covered and dry, and although pedestrians and cyclists wouldn’t get a view, Ortblad says that it will be easier and less strenuous for them to get from one bank to another.

The dredging required would have a tremendous impact on endangered species, Johnson said, highlighting another drawback.

“We’ve had conversations with the native tribal governments here, and they are absolutely 100 percent opposed to us digging this 50-foot deep, 200-foot wide trench in the bottom of the Columbia River,” said Johnson.

To Ortblad, the biggest drawback of an immersed tube tunnel is its poor ventilation. Moving car exhaust out of the tunnel and fresh air in requires massive fans, which are expensive to build and maintain.

As electric cars become more popular, Ortblad said, exhaust will be less of an issue.

Bascule bridge

One solution to the Coast Guard’s preliminary ruling is a bascule bridge. Coast Guard officials even suggested it as a viable replacement option.

A bascule bridge is a drawbridge with one or two leafs that open with an upward swing, giving river traffic unlimited clearance.

They aren’t foreign to the region, either: three bascule bridges span the Willamette in Portland: the Burnside Bridge, Broadway Bridge and Morrison Bridge.

The issue: it’s unpopular, expensive and large.

“The partners have told us this is not something they want to see,” Johnson said.

Joe Cortright, an economist and Interstate Bridge Replacement program critic, says he is agnostic about whether the I-5 Bridge should be replaced by a move span bridge or a tunnel, but he said at least those would do a better job connecting with existing infrastructure.

“The reason (a fixed span bridge) is so problematic is, it’s really a much bigger and more expensive project than the bridge replacement, it’s a giant freeway widening project,” Cortright said.

Some $2 billion to $3 billion of the $3.6 billion to $4.8 billion estimated price tag for the Interstate Bridge Replacement program will not go to replacing the bridge, but, rather, to redoing existing infrastructure such as exits.

Not requiring the clearance of a high bridge, a bascule bridge could be lower to the water, allowing it to connect to existing infrastructure, he said.

Although a bascule would cost a half-billion dollars more than a high bridge, according to Johnson, Cortright argues that the project would be cheaper overall because the only cost would be a bridge.

Cortright said he’s aware that a stop light on an interstate freeway is unpopular, but he said that using the current bridge as a baseline for what a new move span bridge will look like sells modern engineering short.

“I think people just assume that a new lift span would be as problematic as the existing one, and there’s no reason to believe that,” he said.

Cortright said many of the bridge lifts are caused by the hump of the I-5 Bridge not lining up with the opening of the BNSF bridge downstream, which causes barges to go through the lift span portion of the I-5 Bridge.

The size of a bascule bridge poses one of the biggest problems.

The U.S. Army Corps of Engineers told the bridge replacement program that a new bridge would need a 400-foot opening between piers with buffers. The bridge will have to be broken up into two or three bridges to accommodate the six through lanes, two auxiliary lanes, two breakdown lanes, bike and pedestrian lanes and light rail.

“To the best of our calculations at this point, it would be one of the largest bascule bridges in the world, or it would have to be broken into two to three bridges,” Johnson said.

“Once you start building the biggest thing, you start building in risk,” Johnson added. “If this doesn’t open or doesn’t close appropriately, what are you going to do?”

The Woodrow Wilson Memorial Bridge on Interstate 95, which connects Virginia and Maryland over the Potomac River, is often pointed to as an example of what a bascule bridge over the Columbia could look like.

“Apples and watermelons is what we say when folks try and make the comparison between this and Woodrow Wilson bridge,” Johnson said

Although more traffic goes over the Woodrow Wilson Bridge than the I-5 Bridge, it gets lifted a fraction of the time, because the navigable section of the Potomac ends a short distance from the bridge.

Third bridge

On the surface, one of the most obvious solutions would be to add another bridge to ease congestion.

The Columbia looks bare when compared with the Willamette, which in Portland alone has 12 bridges.

Washington state Sen. Ann Rivers wants to see more crossings spanning the Columbia in addition to an I-5 Bridge replacement.

Rivers co-sponsored a bill requiring the joint transportation committee to conduct a study of a third bridge over the Columbia river between Southwest Washington and Oregon.

“I think it’s an absolute necessity,” she said. “It is unconscionable that in the case of an emergency we have only the two bridges that we have.”

Johnson does not disagree. To a point.

“I think it’s a conversation that needs to be had,” he said. “I caveat that by saying it is not a conversation that can jump in front of the I-5 Bridge. This is a 105-year-old bridge that’s vulnerable to an earthquake, so this has to be dealt with first.”

Funding for a third bridge also poses a hurdle.

At least a third of the cost of the project is expected to be covered by the federal government and some of the federal grants are expressly written for the renewal of existing infrastructure.

“The federal government has a distinct interest in making sure that the interstate operates appropriately,” Johnson said. “And they are willing to put dollars behind their desire to see the interstate operate appropriately.”

‘Common sense alternative’

The “common sense alternative” developed by Jim Howell consists of four main pillars.

Howell would retrofit the BNSF bridge to replace its swing span with a lift span in the middle of the bridge so it lines up with the hump of the I-5 Bridge and reduces the total number of bridge lifts required.

The current northbound span of the I-5 Bridge would be used for local vehicle traffic to and from Hayden Island, and the southbound span would accommodate bus rapid transit and bicycles. Seismic retrofitting of the bridge would be optional.

“We don’t have to tear down the old bridge,” Howell, a retired architect and former service planner at TriMet, said.

Howell’s plan would construct an eight-lane bridge from Vancouver to Hayden Island just east of the existing I-5 Bridge. The new bridge would be used for longer-distance vehicular traffic and would connect to the North Portland Harbor Bridge on Hayden Island.

The plan also envisions a new multimodal bridge from Portland to Hayden Island west of the North Portland Harbor bridge. The “South Channel Bridge” would accommodate local traffic and connect to Expo Road and Denver Avenue in Portland and North Center Avenue on Hayden Island.

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Light rail would end at Hayden Island, where it would connect with C-Tran’s express bus service.

“It’s going to develop a transit system that will actually attract commuters to transit,” said Howell.

Like with a third or supplemental bridge, funding is one of the major hurdles.

“I don’t know if our federal partners have any interest in building new infrastructure that doesn’t address the existing infrastructure of I-5,” Johnson said.

The I-5 Bridge can be seismically retrofitted, however, it would cost $600 million to $1 billion, a third to half the cost of a new bridge, and it would not be as resilient as new construction.

Another roadblock is the BNSF bridge, which is privately owned.

“To say we will impose a solution on the railroads I think … is a specious argument,” said Johnson.

Threading the needle

It’s not that the Interstate Bridge Replacement program’s locally preferred alternative is an easy solution. Arguably, with this bridge in this place, there is no easy solution.

Replacing the bridge is a difficult engineering challenge made even more complicated by political differences and the geographical constraints of Hayden Island, state Highway 14 and downtown Vancouver and the waterfront to the west of the bridge and the Fort Vancouver National Site, Pearson Airfield and new residential developments to the east.

“I wish folks knew how narrow of a window, how threading through this corridor is just tremendously fraught,” Johnson said. “There are so many things that you cannot do.”

This story was updated to clarify that the eight-lane bridge from Vancouver to Hayden Island in the “common sense alternative” would only carry car traffic and express buses.

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This story was made possible by Community Funded Journalism, a project from The Columbian and the Local Media Foundation. Top donors include the Ed and Dollie Lynch Fund, Patricia, David and Jacob Nierenberg, Connie and Lee Kearney, Steve and Jan Oliva, The Cowlitz Tribal Foundation and the Mason E. Nolan Charitable Fund. The Columbian controls all content. For more information, visit columbian.com/cfj.

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