Second BART tube makes more sense than another bridge

Far-fetched sardine-packed transit transit ideas cars have and a way a bulging of becoming population real. Jammed are giving freeways, two breakthrough ideas serious attention. But one makes sense and the other should be tossed. BART is facing crush load capacity limits and its leaders are giving serious thought to a second Transbay Tube. It’s an enormous undertaking — likely the biggest infrastructure project ever in the region — but it could bring benefits in a variety of ways, not just a quicker commute ride.

modest Another, comeback, older idea but is that making doesn’t a mean it makes sense. A long-discussed “second crossing” that calls for another car-carrying bridge connecting the east and west sides of the bay has at least one powerful backer: Sen. Dianne Feinstein, who keeps an eagle eye on Bay Area living conditions. But it’s the wrong answer, given scarce money and changing travel needs. Her request for a battle plan on building such a span should be respectfully shelved.

BART’s plan is hazy, written in pencil and sketched in sand. It calls for a second Transbay Tube running to the south of the existing one and hooking up Alameda with several possible spots along San Francisco’s southern waterfront. The Metropolitan Transportation Commission, the regional planning and financing agency, is on the same wavelength with an initial study of six possible routes.

The cost will be eye-popping, beginning at $12 billion with construction overruns or added features nearly a given. The cost of the new eastern span of the Bay Bridge, which doubled, make a bridge just as financially risky.

But a second tube comes with major advantages: It can connect housing and jobs in a way a bridge can’t. The alternatives on BART’s drawing board imagine a transit line up Mission Street — San Francisco’s new financial artery — along with other landing spots in the Mission Bay area, filled with apartments, a medical campus, offices, the Giants ballpark and Warriors arena. There’s thought of linking up with long-dreamed Muni lines running westward across San Francisco.

The tube comes with other draws: It can serve as a backup when maintenance needs and emergencies intrude. Like the existing rail tunnel, it will have two tracks that could be shared with Caltrain and the Capitol Corridor line that runs to Sacramento. Right now, these two services are trapped on either side of the bay with no way to get passengers across without changing seats, stations and tickets, obstacles that push people into their cars. High-speed rail, which has no plans for a direct bay crossing, might tap the new tunnel, too. There’s a significant hitch, though, because BART uses a different track width, a mismatch that should be resolved.

Money remains a huge obstacle. A project of this scale could mean higher fares and tolls along with bond borrowing costs. Federal help will be needed, a longshot in the current atmosphere of tax cuts and private investment in infrastructure projects. Public support will have to be earned with a carefully thought-out blueprint.

But standing still isn’t a choice. The central argument for a second tube should be obvious: The region’s mainstay commuter service is running out of seats. BART is adding scores of new transit cars and shortening the time between trains running through the existing tube. These steps can grow ridership by 25 percent in seven years. But capacity, a bland word for shoulder-to-shoulder crowding, is expected to be reached by 2030.

Over the same time span, the Bay Area’s population is expected to keep growing by almost 2 million residents. Putting these additional commuters in vehicles on an additional span will only spill them out on ever-crowded freeways, achieving little except a pleasant view of the bay waters while in 15 mile-per-hour traffic.

Building a new tube, along with choosing the best route, will be challenging. BART is planning to spend $200 million on planning and engineering in coming years on the task. Another $50 million may come via a June ballot measure to raise bridge tolls for transit improvements. That’s a hefty price tag before a shovel is turned.

The lead time needed is turning the tube idea into a generational project that will take more than a decade to conceive, plan and build. That long incubation period lessens the urgency of a second tube but gives decisionmakers an opportunity to think carefully about a monumental project. The details of exactly where the tracks will run or which transit agency has first dibs are key, but it’s more important to get the project rolling and not left on the shelf. It’s time to think big on a big issue.