Battle of the blueprints: Should I-280 stay or should it go?

Some San Francisco residents are roaring over a study to explore tearing down a portion Interstate Highway 280 in Mission Bay, which could clear the way for a Caltrain extension downtown.

But two sets of blueprints obtained by the San Francisco Examiner paint contrasting futures of I-280, including an effort to put the brakes on the proposal decades ago.

One set of blueprints, drawn in 1969, planners say shows evidence that to build a new Caltrain extension, I-280 must come down — no questions asked.

The other set of plans, two decades old, purportedly shows a road not taken — how the Caltrain extension could be built without the need to tear down I-280.

Meanwhile, the latter idea is gaining support. After a packed public meeting last month when local residents of Potrero Hill and The City’s southeast booed and hissed over the proposal, political heavyweight John Burton, the state’s democratic party chair and a former congressman, joined a chorus of voices denouncing the plan.

“Well, I think it’s stupid,” he told the Examiner of the possibility of tearing down I-280. “It’ll clog up Potrero.”

He’s not alone. Former Mayor Art Agnos previously told the Examiner he would personally launch a campaign against the I-280 teardown if it were pursued.

Planners are now preparing for another meeting on March 30 to discuss the possibility of tearing down the freeway, which they argue will “open up” Mission Bay to the community.

Plan 1: Narrow Freeway Must Come Down

Blueprints of I-280 drawn in the 1960s by the Department of Public Works show one glaring issue, planners argue:

I-280 is too narrow to bore a tunnel underneath.

The blueprints show I-280’s pylons are 24 feet apart. That’s smaller than any train tunnels that could be dug up beneath the freeway, wrote Susan Gygi, in an analysis sent to the Mayor’s Office in February.

Even though the pylons are 24-feet on centerline, “inside spacing — or the width between the edge of a piling to another piling — is less than that,” Gygi wrote in an email to Gillian Gillett, the mayor’s transportation director.

“Big Alma,” the main boring machine used in 2014 to dig the hole for the Central Subway in Chinatown, has a diameter of 22-feet, Gygi wrote. But a single tunnel bore is at least 28 feet in diameter — too wide to fit.

Above, “Big Alma” tweets a photo of its tunnel from the official Big Alma Twitter account.

And forget tunneling two bores around the pilings, she wrote. If that were tried, “you wouldn’t be able to ‘bring them together’ in the space that you have before entering the downtown extension,” Gygi wrote.

Only if I-280’s pylons come down, she argued, would tunneling be possible.

Plan 2: Tunnel a Walkway

When told I-280 must come down, a retired Bay Area engineer had essentially one reply: Nope.

Gerald Cauthen is a retired engineer from consultants Parsons Brinckerhoff Quade & Douglas, Inc., based in San Francisco. While most retirees keep knick knacks from the office, like a favorite paperweight, Cauthen kept blueprints.

Lots of blueprints.

Among them are a set of drawings labeled with the Muni “worm” logo, titled “Phase 1 Design Conceptual Engineering Drawing,” which was last redrawn Nov. 5, 1993.

Cauthen says these plans show another solution to extending Caltrain downtown.

The plans show Caltrain tracks to the Downtown Extension depressed only five feet below the surface, instead of tunneling underground.

To join Mission Bay with the rest of The City, the blueprints feature a construction nowhere else in San Francisco — an underground roadway, and accompanying pedestrian passage.

It’s far better, Cauthen said, than tearing down I-280 and turning the freeway into a boulevard.

“Putting four lanes of northbound freeway traffic headed to downtown San Francisco onto Seventh Street would cause a mess,” he said, “To avoid this, at least half the traffic would have to be diverted farther south.”

But there aren’t any viable alternatives to reroute those cars, he said, which would lead to future traffic snarls in Mission Bay. Mariposa, Third and Cesar Chavez streets as well as other roadways may all encounter traffic burdens under the plan, he alleges.

BLUEPRINTPREVIEW

Blueprints #1: Shows the narrowness of I-280, which planners argue mean the freeway must come down to tunnel. (Click here to view).

Blueprints #2: Shows unused plans for underground roadway/walkway. (Click here to view).

Ed Reiskin, director of transportation at the San Francisco Municipal Transportation Agency, said that plan doesn’t pan out.

“Forcing us to create depressed canyons to connect Mission Bay to the rest of The City would be problematic from a land use and transportation standpoint,” Reiskin said on KALW radio, in mid-March.

Cauthen said, as a counterpoint, “We think you could build the downtown [Caltrain] extension and keep the freeway where it is.”

The mayor’s office and city planners, however, have other ideas.

Looking to the Future

The mayor’s transportation director, Gillian Gillett, wrote to Caltrain in 2013 arguing a need to raze I-280 and relocate the Caltrain railyard to make way for more office and housing development in Mission Bay.

When asked if tearing down I-280 is to benefit development, Gygi told the Save Muni group that failing to plan for more offices and more housing would be inconsistent with projections for San Francisco’s inevitable population boom.

Local group Plan Bay Area gives numbers of anticipated growth to each of the regions, she said, and to San Francisco it anticipated “200,000 jobs and 100,000 housing units by 2040.”

“We’re trending almost five years faster than that,” she warned.

Those new people will have to live and work somewhere. The question is, whether they’ll have a view of I-280 in their backyard.CaltrainI-280Interstate 280Mission BayPlanning DepartmentTransit

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