Seven people were injured Wednesday morning when a San Francisco Municipal Railway cable car struck a bolt lodged into the tracks, according to authorities.
The bolt was stuck in the trackway, causing the inbound Powell-Hyde cable car to stop abruptly on Powell just before Washington streets around 10:15 a.m., San Francisco Municipal Transportation Agency Director of Transit John Haley said.
The 2-inch bolt was jammed at the top of the tracks, about 6 inches above the underground cables that are covered in sensors that trigger an alarm if there is an obstruction.
The alarm alerts operators to stop the cables, according Haley.
In Wednesday's case, the bolt never touched the sensors.
The alarm is usually triggered as many as two to three times a day, Haley said, however the crews usually find trash, such as a hot dog wrapper, that makes its way deep into the tracks.
After the bolt suddenly halted the cable car, five passengers and two cable car operators were transported to the hospital with minor injuries, San Francisco fire spokeswoman Mindy Talmadge said.
One of the injured passengers was a man in his 80s who suffered a head injury, Talmadge said.
After a review of the incident, Muni inspectors have determined the bolt had come lose from a switch plate covering a portion of the tracks, Haley said.
Haley said there was nothing wrong with the cable car vehicle itself, however the car did sustain some damage in the incident and is undergoing repairs to its underside.
It is expected to be back in service within the next three days, he said.
The bolt incident has prompted a review of the track maintenance system, Haley said.
The more than 40 switches part of the cable car system are checked each night and now a weekly check will test the tightness of the bolts securing the switch plates, he said.
Bus shuttles were in place for passengers on the Powell-Mason and Powell-Hyde cable car lines through early Wednesday afternoon the while officials inspected the cause of the accident.
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