Tacoma presses its Sound Transit agenda. That’s wise. But an underground station? That’s questionable

Eleven more years feels like an eternity to wait for light-rail trains to arrive in Tacoma. Impatience is natural for South Sounders, especially since we’re already paying higher car-tab fees in the wake of voters approving the $54 billion Sound Transit 3 mega-project in 2016.

But in the complicated world of transportation infrastructure planning, 11 years really isn’t such a long time. That’s why the City of Tacoma and community stakeholders are getting busy drafting recommendations for the Tacoma Dome Link Extension Project.

Local leaders must be thoughtful, thorough and nimble while providing Sound Transit with timely input for route alignment and station location alternatives. They also need to be cautious before espousing ideas, such as an underground station, that are popular but not necessarily practical.

By this summer, Sound Transit is expected to define the scope of work for an environmental impact study. Before then, the community must lay down clear markers of what it wants to see — and what it won’t tolerate — in a light-rail extension from Federal Way to Tacoma, set to open in 2030.

Respecting property rights, promoting transit-oriented development and protecting the social fabric of urban neighborhoods will be key.

The process, which has been fairly low-profile so far, will get some needed sunlight when it comes before the City Council on June 11. Those who’ve been involved to this point include Pierce County, the Port of Tacoma, Pierce Transit, the Dome Business District and the Puyallup Tribe of Indians.

Now’s the time for members of the public to share hopes and concerns. A draft copy of the city’s recommendations accurately captures the historic nature of the project, calling it “a 50-plus-year decision on investments that are made only once every few generations and which can and will have a dramatic effect on this community.”

We appreciate some of the priorities highlighted by community leaders — and some of the lines they’ve drawn in the sand.

Strong pedestrian connections to neighborhoods south of Interstate 5 should be factored into Sound Transit’s plans, as well as good access to bike corridors, trail systems and other transit links. Likewise, the need for adequate parking for light-rail commuters must not be shortchanged.

The city also should identify landmarks it wants preserved, an inventory already under way. “Sound Transit should recognize that Freighthouse Square is an iconic structure and avoid physical destruction to it, unless it can be functionally and aesthetically incorporated and enhanced as it was through the Amtrak Station project,” the draft resolution states.

A few words of caution are warranted, however, before people fall madly in love with the idea of building an underground station in Tacoma, also known as the “cut and cover” option.

This design has been used on some Sound Transit projects up north; it’s ostensibly less disruptive to neighborhoods while leaving more space for housing units and other transit-oriented development at street level. Stakeholders in West Seattle, where light-rail service is scheduled to start the same year as Tacoma, are talking about it, too.

There’s nothing wrong with asking Sound Transit to study the costs and benefits of going underground. But be forewarned that doing so could be a budget buster — subterranean trains typically cost two to three times more than elevated routes — and our region’s history of tunnel construction fiascos is instructive.

Undergrounding tends to send transit projects into overtime. And as we’ve been saying for nearly three years: Extending light rail to Tacoma by 2030 is a deadline that must not be missed. Eleven more years is plenty long enough for South Sounders to wait for a return on their very big investment.