Interstate 5 tunnel: To be or not to be?

“It just didn’t do as well as any of the options that were being looked at that were bridge-related.”

Columbia River Crossing project staff started working with the public, stakeholders and governments in October 2005 to articulate what, at a minimum, an alternative to the existing I-5 Bridge needed to do.

Planners wanted to know whether a given solution would:

• Increase vehicular capacity or decrease vehicular demand

• Improve transit performance

• Improve freight mobility

• Improve safety and decrease vulnerability to traffic incidents

• Improve bicycle and pedestrian mobility, or

• Reduce the seismic risk of the I-5 crossing.

In April 2006, staff looked at the 37 transit and crossing options they had gathered, and eliminated 22 of them. Eventually, they designed a 10-lane toll bridge with light rail and paths for bicycles and pedestrians. But in 2014, Republicans in the state Senate refused to fund Washington’s share of construction, and the project eventually was canceled.

Connecting the projects

The Columbia River Crossing project, Strickler said, was as much about connecting the areas at each end of the crossing as it was about getting across the river.

Even today, a new crossing would need to connect the freeway with state highways, downtown, the waterfront and elsewhere.

Meghan Hodges with the Washington State Department of Transportation, and Carley Francis, the agency’s Southwest Region administrator and then-spokeswoman for the crossing project, said the geometry of a tunnel would preclude that.

A tunnel would have to run well below the river’s 40-foot channel depth. To maintain a standard interstate highway grade, the tunnel would have to surface around Mill Plain Boulevard in Washington and south of Marine Drive in Oregon.

“By the time you get up to the roadway surface, there’s a good chance you’ve bypassed all of downtown,” Strickler said.

The new tunnel entrances would need whole new systems of connecting roads to state Highway 14, downtown Vancouver, Hayden Island and Marine Drive.

For example, Hodges said, state Highway 14 would need to be extended north to Mill Plain, which would require purchasing additional surrounding land. That would presumably include part of the Fort Vancouver National Site.

“These connections would also require significant out-of-direction travel for many users, including vehicles, transit, and bike/pedestrian travelers,” she wrote.

Hodges and Francis also noted that there would actually need to be two tunnels, north and south, to handle all of the demand.

Supplemental tunnel

So what about keeping the existing bridge and adding a tunnel for through traffic?

That idea was studied and dropped, “as it had marginal transportation benefits, considerably lower highway safety performance, very high capital cost, and higher community impacts,” according to the final crossing report.

Furthermore, planners said, much of the existing river traffic is local. Based on CRC studies, at least half of the freeway traffic would still end up on the existing bridge, which would still have the same performance and safety problems.

Again, the question isn’t necessarily whether a tunnel is technically feasible. Builders put a train tunnel under the English Channel and a 15-mile highway tunnel, the world’s longest, through a Norwegian mountain range. They could certainly burrow under the Columbia River.

“I decided that it wasn’t a very good idea,” he said.

Beyond the problems of tying in other roadways and new frontage roads, a supplemental tunnel plan comes with potential earthquake hazards, he said.

“I would like to see it all go underground, but the expense of doing it — that’s a pretty big chunk of change,” he said.

He’s a tunnel fan, he added, but they’re probably not tenable for much of the region due to politics and the way the cities have grown.

About the only talk of a tunnel he sees anymore, he joked, are in letters to the editor.

“Tunnels are very good,” he said, “if you put them in the right place.”