A San Francisco Bay Area Planning and Urban Research Association (SPUR) board member spurs discussion of a third transbay BART bridge in addition to the proposed second BART tunnel.

SFist is a sucker for fantasy transit maps cooked up Redditors with no civic planning backgrounds, so we can dream of things like taking BART to the Presidio, Golden Gate Park, or the SF Zoo. But legitimate, reality-based plans to build a second BART tunnel have been discussed by the BART board since around 2014. We’ve seen proposals for a second tunnel that would turn east instead of north at 16th & Mission Station, heading to Alameda island and beyond, but nothing has ever been formally approved. The dormant second tunnel discussion perked back up this past November at a series of BART board meetings, and the Chronicle said it was a question of “when, not if” that second tunnel would be built.

Now a board member of the influential urban planning nonprofit SPUR proposes a third way across the Bay, with a peninsula-to-south-Alameda-County BART “aerial bridge” (the green line seen above) that could be built quickly, and for peanuts compared to BART’s other proposals.

SPUR board member Bryan Grunwald is an East Bay architect and planner at his own private firm, and according to his LinkedIn, has not been affiliated with a sanctioned government project since 2005. But Grunwald loves pitching out-of-the-box ideas that would never occur to bureaucratic pencil-pushers, like an Oakland A’s stadium built on top of I-980. And he does have a point that BART was built to transport 250,000 people a day, now transports 400,000 a day, in a way that’s out-of-line with where populations have increased.

“I propose an aerial structure and bridge (AS&B) that connects the Bay Fair Station with the Millbrae BART Station,” Grunwald writes in true Medium-post fashion, in a guest post for Berkeleyside. "This route would be 16 miles and take about six minutes at 160 mph, double the current BART speed of 80 mph. This proposed crossing and higher speeds would make the Fremont/Warm Springs and Dublin/Pleasanton stations equidistant from the downtown San Francisco stations.”

To Grunwald’s credit, Fremont and Dublin are the areas where the Bay Area population is growing most rapidly, so it does make sense to give them a dedicated side route.

Moreover, this plan would be incredibly cheap and quick compared to whatever sort of multiple-decades boondoggle the proposed second BART tunnel would be. It’s just a bridge connecting two existing stations. There are no new stations that would need to be added, no underground tunnel digging, and no disruption of any current traffic or travel patterns.

The still-also-theoretical second BART tunnel is currently projected to cost $50 billion, whereas Grunwald’s bridge would cost just $3 billion. Hell, a BART project can hit a $3 billion cost overrun before lunchtime on any given Tuesday. He notes that there’s $3.5 billion just sitting there already existing in Measure RR BART Bond funding. “A new tube with additional stations is unnecessary and will take years to fund and build,” Grunwald writes on Berkeleyside. “The proposed bridge would take a tenth or less time to build. We need congestion relief now.”

Related: Problematic Sharp Turn In Oakland BART Tunnel All Thanks To A 1960s Political Compromise [SFist]