Another Tunnel? Sound Transit Debates Where To Put Trains

This fall, voters will decide whether to extend Sound Transit’s light rail farther, like to Everett and Tacoma. The ballot measure is called Sound Transit 3.

Planners are deciding now where to put the trains that the measure would bring into Seattle because there isn’t enough room in the existing downtown transit tunnel.

The new trains could go in a new downtown tunnel – not like the tunnel Bertha is digging – but a smaller train tunnel. Cities build that kind of tunnel all the time, but they’re still expensive. So officials are looking at other options.

Standing on First Avenue, Val Batey, a senior planner with Sound Transit, says this is one place Sound Transit could run trains serving West Seattle and Ballard.

“Surface street light rail would, depending on how it’s designed, operate much like it does in the Rainier Valley,” Batey says.

There are many reasons Sound Transit is exploring this option, including price.

“The surface alignment would be less expensive,” Batey says.

Batey, who is officially neutral on the plans, says there are other benefits to the surface option. You could board a surface train without descending into the bowels of the earth. And light rail might be able to share tracks with the new streetcar that the City of Seattle hopes to install on First Avenue.

That wasn’t possible in the past, because streetcars and light rail used different power sources. But some of Seattle’s streetcars operate on battery power for part of their journey.

“Technology is changing all the time," Batey says. "By the time we get to actually designing and building this, there may be more options available to us to combine transit.”

It wouldn't be the first time First Avenue was covered with rails. This photo from 1920 shows the streetcars that brought passengers down this street.

But the surface option has drawbacks. For one, it’s less reliable. And what if an accident blocks an intersection? What if a human dashes out in front of the train? That happened in Rainier Valley. And it’s even more likely downtown, where there are more humans.

“Humans don’t always pay attention to the warning signs,” Batey says.

That’s one reason Sound Transit is considering the tunnel option.

“With your exclusive right of way,” Batey says, “you have much more control over what’s going on down there, and so your trains and your service are much more reliable.”

Sound Transit has done enough engineering on this idea to know the new tunnel would run under the existing downtown transit tunnel. From downtown stations, you could transfer underground to lines serving Everett, Tacoma and Bellevue.

Sound Transit hopes to have a decision on whether to pursue a tunnel – or a surface street route – by the end of March. It’ll collect feedback on the plan in April.

What do you think? Should we go with the tunnel or surface street option? Join the discussion on our Facebook page:

Should light rail expand via tunnel or surface street? (Does this question seem familiar?)Posted by KUOW Public Radio on Wednesday, February 10, 2016