Photo: Transbay Joint Powers Authority Photo: Michael Cabanatuan / The Chronicle Photo: Paul Chinn / The Chronicle Photo: Eric Risberg / Associated Press Photo: Michael Cabanatuan Photo: Paul Kuroda / Special To The Chronicle Photo: Jessica Christian / The Chronicle Photo: Jessica Christian / The Chronicle Photo: Jessica Christian / The Chronicle Photo: Yalonda M. James / The Chronicle Photo: Paul Kuroda / Special To The Chronicle Photo: Yalonda M. James / The Chronicle Photo: Paul Kuroda / Special To The Chronicle Photo: Jessica Christian / The Chronicle Photo: Jessica Christian / The Chronicle Photo: Yalonda M. James / The Chronicle Photo: Yalonda M. James / The Chronicle Photo: Yalonda M. James / The Chronicle Photo: Yalonda M. James / The Chronicle Photo: Paul Kuroda / Special To The Chronicle Photo: Yalonda M. James / The Chronicle Photo: Yalonda M. James / The Chronicle Photo: Paul Kuroda / Special To The Chronicle Photo: Yalonda M. James / The Chronicle Photo: Yalonda M. James / The Chronicle Photo: Yalonda M James / The Chronicle Photo: Yalonda M James / The Chronicle Photo: Yalonda M. James / The Chronicle Photo: Paul Kuroda, Special To The Chronicle

Fremont Street will stay closed for at least 10 more days where it passes beneath San Francisco’s broken Transbay Transit Center, ensuring at least 10 more days of traffic tie-ups.

Christine Falvey, Transbay spokeswoman, said officials are aiming to open a narrowed Fremont Street between Howard and Mission streets by Oct. 12. They offered no date for reopening the transit center itself and its rooftop park, but they said it likely would be at least three weeks.

The $2.2 billion transit hub and Fremont Street were hurriedly closed the evening of Sept. 25 after workers installing ceiling panels discovered a cracked support beam. A second cracked beam was discovered in the same area — where the center spans Fremont Street — hours later.

The shutdowns came just six weeks after the opening of the three-block-long center, which features a rooftop park and has been dubbed “the Grand Central Station of the West.” Bus riders and neighbors have praised the center and particularly the park, and are eager for them to reopen.

The Transbay Joint Powers Authority, which built and operates the transportation hub, had originally hoped to have it reopened by Friday. Transbay officials expect to announce details at a special meeting of the TJPA Tuesday morning.

Dennis Turchon, senior construction manager for the TJPA, was reluctant to offer specific dates at a press briefing Monday afternoon, saying transbay officials need to finish reinforcing the damaged section of the center before they can make plans for repairs.

Crews installed temporary shoring Sunday using six hydraulic jacks perched atop a 10-foot-wide wooden pad in the center of the street.

The jacks will be replaced within days by a sturdier temporary support structure consisting of two steel-pipe towers that will sit in the middle of Fremont Street. Similar towers will be installed inside the terminal between the bus deck and the roof.

The towers are being fabricated in Stockton by Herrick Corp., the company that provided the girders that cracked, Turchon said.

“It’s a warranty-type issue and they have the most knowledge about the project,” he said.

Engineers have already conducted magnetic and ultrasonic tests on the two cracked girders, Turchon said, but have to wait to perform metallurgical and other more telling tests until the weight supported by those beams is completely transferred to the temporary support systems. That’s expected to take about a week.

Testing could another take two weeks, Turchon said. Then engineers need to devise a permanent fix for the beams, which could require weeks more. While it’s too early to speculate on the strategy, he said the beams will not be removed and replaced. What’s more likely is that additional steel will be added to bolster the damaged girders.

When Fremont Street reopens, the three-lane road will be narrowed to two lanes squeezing past the 14-foot-wide support towers in the center lane. Transbay officials are working with the Municipal Transportation Agency to reconfigure the street, Turchon said. The current 12-foot lanes likely will shrink in width.

But the permanent fix to the transit center would not involve any structures remaining on Fremont Street, Turchon said emphatically.

The beams are just the latest trouble for the Transbay Transit Center, also known as Salesforce Transit Center. Construction delays, cost overruns and a crumbling granite sidewalk on the rooftop park have plagued the project.

So has the lack of a rail connection, planned to bring Caltrain and eventually high-speed rail to a basement station in the center. The center has an empty area known as a “rail box” beneath the station with room for tracks and station platforms.

San Francisco Supervisor Aaron Peskin said Tuesday that he wants the San Francisco County Transportation Authority, a planning and programming agency controlled by the Board of Supervisors, to stop giving money to the TJPA for the rail extension, considered the second phase of the Transbay Transit Center.

Peskin said he wants transportation officials to look at how similar large-scale projects are built around the world and consider creating a new agency to oversee the project.

“This is an opportune time to force a conversation, given the train wreck of events,” he said. “It’s time to call a timeout and look at a more appropriate governance structure.”

Peskin made it clear that he does not want to cut funding for the repair of the Transbay Transit Center’s broken beams.

“An emergency is an emergency is an emergency,” he said.

Michael Cabanatuan is a San Francisco Chronicle staff writer. Email: mcabanatuan@sfchronicle.com Twitter: @ctuan