Imagine, for a moment, stepping onto a light-rail train on Ballard Avenue that, following a few beeps and boops and “doors closing”s, whisks you toward Downtown. Around Queen Anne the train ducks into the black of a tunnel that runs beneath Downtown all the way to SoDo. From there it comes back to ground level and brings you over the Duwamish, to the end of the line in West Seattle.

There are two important points to understand about this: First, it’s a real idea, and probably a really good one; second, it may well not come to fruition before Kylie Jenner is eligible to be president (2033. Mark your calendars). And those two facts alone go a long way to explain both the hope and frustration that can be expected in the months to come as the Greater Seattle region begins to contemplate how it should shape mass transit over the next few decades.

The concept of what amounts to a subway line from Ballard to West Seattle through a new Downtown tunnel is being championed by a group called Seattle Subway. Around for more than two years, it’s run entirely by volunteers obsessed with seeing Seattle get the mass-transit system a city of its size and stature deserves. But over the past few months, with the state legislature wrestling over how much taxing authority Sound Transit should get for its next massive wave of capital improvements (no figure of fewer than 11 digits is on the table), Seattle Subway has been pushing its agenda more aggressively, laying out a host of knotty demographic figures that add up to a good case for the necessity of a Downtown Seattle transportation system like this.

To avoid drowning in those figures, Seattle Subway’s basic point is this: Seattle’s population is expected to continue to explode because of jobs Downtown, and many of those workers are expected to live in Ballard and West Seattle. Simply running more and more buses into a Downtown that’s already at capacity for surface transportation won’t work, and buses alone won’t be able to handle the demand Sound Transit projects for downtown by 2035 (a 2014 study showed that even high-capacity transit like light rail running between West Seattle, Ballard and Downtown, Downtown transit would fall short of demand by 5,000 to 8,000 trips a day). So you need a tunnel, and you need high-capacity trains running in it. With that in mind, they are proposing that Sound Transit start building the tunnel now, run buses in it to begin with, then eventually transform the tunnel into the rail system envisioned above (though it would have rail installed from day one).

“If people don’t want jobs, we can keep our transportation system a mess. If they want the city to continue to grow and prosper, we have to build a new tunnel,” says Jonathan Hopkins, a West Point graduate and army vet who volunteers with Seattle Subway. “The alternative is just be stuck on buses and cars on the surface. That’s not how you move people in a world-class city.”

Seattle Subway is a serious group, and is devoted to more than just the new downtown tunnel. But it’s presented its tunnel plan to the advisors of most relevant policy leaders, and those leaders remember who they are. Dubious gauge of relevance though it may be, the group has managed to get 7,400 likes on Facebook. Speaking of policy leaders, that’s more likes than Ed Murray and Dow Constantine have combined—pretty impressive for a page essentially devoted to long-range transportation planning.

If nothing else, Seattle Subway’s broad appeal shows in part how frustrated city residents have become with its public-transportation system—decades of old wounds crying out for catharsis. But frustration—nor good data—alone won’t make the tunnel a thing. In fact, the obstacles before it speak to why those deep frustrations exist in the first place, and why they may well run far into the future.

First, there’s Olympia. Republicans who control the Senate—most of whom don’t live in the Seattle area, but consider their conservative brethren here a persecuted minority needing their antitax protection—want to give Sound Transit the authority to raise only $11 billion with the ST3 levy. House Democrats and Gov. Jay Inslee continue to push for the $15 billion Sound Transit has requested. A final figure is expected out of Olympia shortly. Hopkins says anything less that $15 billion for ST3 will render his group’s proposal a nonstarter. (“At $11 billion, the discussion becomes, ‘Who gets served? Ballard or West Seattle? And who gets left out?’ ”)

But even if Sound Transit gets the full $15 billion, regional politics will come into play. Voters from Everett to Tacoma will need to approve the $15 billion levy, and if too much money is devoted to inner-Seattle transit, the levy risks being voted down. The Seattle Subway plan hasn’t been studied enough to be assigned a solid price tag, but building the tunnel and outfitting it with rail is expected to carry a substantial cost.

And since the region is still playing catch-up on transit projects that were needed decades ago, building for future needs might not be a luxury Sound Transit can afford.

“The list of things that we can accomplish in Seattle is a pretty long one. The list of things we’d like to include in ST3 is a pretty long one. Financially, there’s not a way to accomplish all those things with an ST3 package,” says Chris Arkills, transportation policy director for King County Executive Dow Constantine. That list also includes popular proposals like light rail from Ballard to University of Washington and rail running down to White Center.

“It’s too early to say right now what’s in the mix,” Seattle city councilman and Sound Transit boardmember Mike O’Brien said Friday, adding that all eyes are on what comes out of Olympia. “If it’s less that $15 billion, it’s going to be a messy fight.”

And among the non-policy-wonk crowd, the building of another Downtown tunnel is sure to raise the hackles of those who’ve watched in wonderment as Bertha ground to a halt in her pursuit of underground transportation. But as with most things, Seattle Subway has figures at the ready to push back against that argument.

“Trains are 1/7 of the size of Bertha,” Hopkins says. “It’s like comparing building a house to a skyscraper.”

dperson@seattleweekly.com