Cable cars return Saturday after fire suppression system havoc

San Francisco’s cable cars will run again Saturday after a problem with the fire suppression system shut down operations last week, transit officials said Thursday. Cable car revenue service had just returned Sept. 4.

Jeffrey Tumlin, the San Francisco Municipal Transportation Agency’s director of transportation, said in a tweet:

“Thanks to our maintenance crews who found a workaround to reopen cable cars this Saturday while we wait for replacement parts.”

A blog posted Monday on the agency’s website said the fire suppression system initiated in an electrical room at the Cable Car Barn on Sept. 9, causing the room to fill with fire retardant material resembling smoke, and prompting fire department response.

The fire suppression release automatically triggered other safety systems, resulting in loss of power to the entire facility and propulsion system suspension, the agency wrote.

The agency attributed the problem to an old release valve that had not been changed since the Cable Car Barn’s last renovation in the 1980s, adding:

“Regular inspections by outside fire safety experts of the fire suppression system have not shown any signs of defect, but the system is almost four decades old and is not considered current best practice.”

According to the agency, the fire suppression system did not sustain any damage. However, it will take time to purchase and assemble necessary replacement parts and more time to inspect and test the system when repairs are complete. Officials originally estimated it would take the end of next week to resume service, but added they were seeking near-term solutions and credited crew workaround solutions.

Officials said plans have been underway for more than a year to complete a major overhaul of the cable car system, including Cable Car Barn renovations and street infrastructure improvements, including tracks and turntables. It is estimated the complete renovation project will cost $625 million.