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Muni Forced to Redo Part of $52 Million Tunnel Project – Just 2 Years After Finishing It

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A 2007 view of Muni's Twin Peaks Tunnel at the Forest Hill Station.  (Jef Poskanzer/Wikimedia Commons)

San Francisco’s Municipal Transportation Agency will be forced to redo part of a $52 million tunnel project because of a decision during construction two years ago that has led to potential stability problems along tracks used by several Muni light-rail lines.

Fixing the track work on the Twin Peaks Tunnel — a high-profile project marked by a series of difficulties, including the death of a worker struck by a falling beam — could cost tens of millions of dollars.

SFMTA officials first disclosed the issue last month to the agency's board. The potential cost was first discussed publicly Tuesday during an SFMTA presentation to the San Francisco County Transportation Authority board.

The tunnel project included seismic retrofitting of the 2-mile-long structure, which first opened in 1918, and replacement of its 50-year-old track structure, including rails, ties and the ballast rock that provides a stable rail bed and allows water to drain from the trackway.

Julie Kirschbaum, the SFMTA’s director of transit, told the Transportation Authority board, a body made up of all 11 members of the Board of Supervisors, that instead of replacing the ballast rock during the project, as specified in the project contract, “a decision was made” to reuse the ballast that had been in place for decades.

“If the ballast had been cleaned and kind of shaken out so that all of the mud and fine particles were removed, reusing the ballast probably would have been a cost-effective and time-effective strategy,” Kirschbaum said. “But it wasn’t. And as a result, we now have ballast that is really more mud than rock and needs to be addressed.”

In an answer to a question from Supervisor Rafael Mandelman, Kirschbaum said the cost of having a contractor go in and replace the ballast would be in the millions of dollars.

“Millions or tens of millions?” Mandelman asked.

“I think tens of millions,” Kirschbaum said.


In her initial presentation on the issue, during an Oct. 20 SFMTA board meeting, Kirschbaum said that when the tunnel work began in 2018, contractors discovered the old ballast was contaminated with a higher level of heavy metals than had been anticipated. That made the ballast "more costly to handle and more costly to dispose of," she said.

"In order to keep the project on-time and on-budget, the decision was made to reuse rather than replace the ballast," Kirschbaum said in October.

Mandelman noted Kirschbaum’s statement on Tuesday that “a decision was made” to reuse the uncleaned ballast and asked her who was responsible. Tom Maguire, the SFMTA’s director of sustainable streets, said the decision had been made jointly by agency staff and the project's contractor, a joint venture involving Oakland's Shimmick Construction and San Francisco-based Con-Quest Contractors.

“They had to weigh a couple of tricky issues in the field, including the possibility that some of the material might be contaminated and might need to be removed,” Maguire said. “However, that critical decision needed to have been elevated sooner and faster with a comprehensive view of all the risks” involved in leaving the old ballast in place.

Maguire told the SFMTA board in October that the agency was discussing the issue with the City Attorney's Office "and figuring out how to hold the contractor accountable."

"A competent contractor should be able to do work like this right," Maguire told board. "This is basic rail construction."

In her own October presentation to the SFMTA board, Kirschbaum said that while the ballast problem didn't pose an immediate safety problem, inspections have determined that track stability issues are likely to develop in one particular location in the tunnel's eastern half.

"Where we know it's going to erode first based on visual inspections and what we've seen over the last two years is around the Eureka Curve," between the Forest Hill and Castro stations, Kirschbaum said.

'Out of Excuses'

Tuesday's details about the tunnel issue emerged just days after the SFMTA acknowledged that its long-delayed Central Subway project will blow through another completion target date and likely not open until 2022.

The Twin Peaks Tunnel problem, on top of delays in other major projects and an embarrassing August mishap in which spliced electrical wires derailed the SFMTA's attempt to relaunch Muni Metro light-rail service, prompted an exasperated response from Supervisor Aaron Peskin, who chairs the transportation board.

"If this were just the Central Subway ... I'd be frustrated," Peskin said. "But when you add the ballast in the tunnel, and when you add the — frankly, I'm going to say it — screw-up relative to the splices, when you add that to the Van Ness BRT (bus rapid transit) delays, which is nowhere near as complicated as these other projects, you're just, as I said in the newspaper the other day, you're out of excuses."

SFMTA officials didn’t immediately respond to questions about when the ballast replacement work will begin. Except for its brief, troubled reopening in August, all Muni Metro light-rail service has been shut down since shortly after COVID-19 shelter-at-home orders were imposed in March.

Related Coverage

The Twin Peaks Tunnel work took place during the summer of 2018 and was marked by a series of missteps and one construction tragedy.

Muni's use of bus shuttles to replace light-rail service through the tunnel during the two months of construction exposed a major shortage of coach operators and threw citywide bus service into disarray.

As work on the project was near completion, a falling beam killed Colusa County construction worker Patrick Ricketts, 51. That brought to light a long history of safety violations by Oakland-based Shimmick Construction, one of the project's principal contractors. Cal/OSHA fined Shimmick and its joint venture partner in the project, San Francisco-based Con-Quest, $65,300 for safety infractions related to Ricketts' death.

When the tunnel reopened, service was subject to repeated delays attributed to problems with trackside train control equipment. After nearly three weeks of frequently disrupted service, Muni said that a contractor's crew had damaged the trackside equipment while doing follow-up work on the project.


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