Why Highway 99 got pulled from our seismic lifeline — despite the new tunnel

Soon, state Route 99 — and the rest of us —will have a new asset: a completed Alaskan Way tunnel.

The $3.2 billion tunnel provides an earthquake-safe route under our downtown. However, the state highway department says it’s taken the highway off its list of Seismic Lifeline routes.

That leaves Interstate 5 and Interstate 405 as our region’s rescue routes following a major earthquake.

SR 99 used to be listed as an alternative route. But John Himmel, WSDOT’s emergency operations manager, said its two lanes in each direction is too small.

After a big quake, the state needs the interstates for big stuff, like supply convoys. They'll also need to get emergency vehicles in and evacuated people out.

That's not to say that I-5 and I-405 don't have issues. As KUOW's John Ryan has previously reported, those interstates are built on hundreds of hollow columns that could cause the highways to collapse in a major earthquake.

And Washington is well behind California in retrofitting its highways and bridges.

But there is good news: The state says a team of engineers at the University of Washington is solving that problem, and there’s even an expectation that the retrofit will be relatively affordable. It’s expected we’ll know more this fall.

If you're asking yourself how you and your loved ones will get out, Prof. Marc Eberhard said you shouldn't necessarily expect to evacuate the city following The Big One.

Eberhard is a professor at the University of Washington and a structural engineer who has seen the aftermath of big quakes.

He said people tend to stay in place because they need to take care of their homes and get back to work.

“It’s about your personal recovery, but it’s also about the community recovery," Eberhard said. “The city itself needs to come back. Economically, socially — you need to have people there."

And when it comes to getting the city moving again, the Alaskan Way replacement tunnel will be indispensable.