Update, April 4, 2019: MTC Executive Director Therese W. McMillan this week sent a new letter to San Francisco Mayor London Breed and to Oakland Mayor and MTC Commissioner Libby Schaaf with an update on progress made by the MTC-assembled expert Peer Review Panel (PRP) in its work to investigate the cause of the fracturing of two girders at the Salesforce Transit Center in San Francisco and to review repairs to these girders. The letter summarizes the panel's findings to date and clarifies the scope of expectations for future findings and recommendations.
"There is broad consensus among the Peer Review Panel and TJPA (Transbay Joint Powers Authority) consultants on the conditions that caused the fractures," wrote McMillan. "There is also agreement on the design of the girder repair at Fremont Street and retrofit at First Street. The TJPA staff recently announced it believes the steel subcontractor is the party responsible for the fracture based on a series of decisions and actions associated with fabrication of the holes cut in the flanges of the girders. This statement reflects TJPA's interpretation of code and contractual terms and responsibilities. Note that the Peer Review Panel was not asked to and does not intend to address this line of inquiry concerning which parties were responsible for the fractures, and whether the work was in compliance with code or contract provisions."
"The Peer Review Panel will continue with its directive to understand the failure mechanism and ensure the repairs are appropriate," McMillan continued. "At the present time, the repair and retrofit are being installed. Concurrently, TJPA staff is searching through records and performing new inspections as necessary to determine if there are other locations susceptible to brittle fracture, and whether any additional retrofits are required. The Peer Review Panel has concurred with the criteria being used for this search and will review the results. In addition, MTC has asked the Peer Review Panel, as it completes its work, to comment on lessons learned from this incident. These will likely take the form of rather broad recommendations on issues this panel believes should be considered by the industry to help avoid this type of failure in the future."
Update, February 8, 2019: MTC Executive Director Steve Heminger today sent a letter to Oakland Mayor Libby Schaaf, who also serves on the MTC Commission, and to San Francisco Mayor London Breed with an update on the work of the MTC-assembled expert Peer Review Panel (PRP) that is examining the causes of and proposed repairs for the fractured girders at the Salesforce Transit Center.
"The PRP concurs with the initial hypothesis on the cause of failure as based on the analysis of material test results: that the fractures were caused by the combination of specific material properties, existence of an initiating crack and stress in the girder," Heminger wrote.
"TJPA's (Transbay Joint Powers Authority) engineer of record, Thornton Tomasetti, has developed a repair that bolts new plates across the fractured surfaces of the two girders over Fremont Street. In addition, enough similarities exist between the condition of those girders and two girders over First Street that the TJPA plans to retrofit the First Street girders in a similar manner," he continued.
Per the letter, "The PRP recommended and the TJPA project team has initiated a search through construction documents for other locations at the facility that might have the same combination of factors that contributed to the girder fractures." Read the full letter here.
Below is the original story that was posted February 7, 2019, and adapted from a Transbay Joint Powers Authority press release.
The Transbay Joint Powers Authority (TJPA) announced on February 1, 2019, that repair and reinforcement work is underway to address the fractured steel beams at the Salesforce Transit Center, the new hub located along a three-block stretch in San Francisco's South of Market area.
MTC’s independent Peer Review Panel approved the repair strategy in December 2018.
The TJPA temporarily closed the Transit Center after cracks were discovered in two steel beams above the third-level Bus Deck in late September 2018, along a segment that crosses over First Street. Two shoring systems were installed, one at Fremont Street and, as a proactive measure, another at First Street, a similarly designed area of the Transit Center. Additional inspections and continued monitoring have revealed no additional issues.
Steel plates to reinforce the cracked beams are currently being fabricated offsite and will be delivered to the Transit Center in March 2019 for installation.
TJPA expects the repairs to be completed by the first week of June 2019 and then the shoring systems at both Fremont and First streets will be removed. A reopening date for the Transit Center has not yet been determined.
MTC’s independent Peer Review Panel is overseeing the TJPA’s review of thousands of building-wide shop drawings, inspection reports and design documents that will determine if any other inspections will be necessary before reopening. After this is ascertained, the TJPA will announce a reopening date.
“Beginning repairs at the transit center marks a major milestone toward reopening the facility,” said TJPA Executive Director Mark Zabaneh. “While we are eager to welcome the Bay Area back to the Transit Center, we are balancing this with our responsibility to undertake an appropriately rigorous inspection and review protocol and cooperate with the independent review of the facility.”
The Salesforce Transit Center originally opened in August 2018 and is currently configured to accommodate several intercity bus systems operating in the Bay Area as well as S.F. Muni lines, and ultimately will also serve as a rail hub.
Until the Transit Center reopens, transit operators will continue to provide bus service out of the Temporary Transbay Terminal at Howard and Main streets. Transit information is available at 511 or 511.org.