The site of a Muni light-rail derailment that marred travel Tuesday is close to where a similar incident occurred in 2006, though officials from the transit agency are still investigating why the L-Taraval train came off the tracks this time.
Investigators were working Tuesday night to figure out how and why the second car of a two-car train ended up partially off the tracks at 7:35 a.m. Tuesday about a mile west of the Castro station but shy of the Forest Hill Station.
No passengers were reported to have been injured when the train came off the tracks. The passengers were all put onto the first car of the train, which was detached and shuttled the riders to Forest Hill. The derailing vehicle severed the communications cable in the tunnel for the train control system and forced the rear light-rail vehicle about a foot off the ground.
The entire Twin Peaks Tunnel between Castro and West Portal station was shut down for the day, with bus shuttles being offered for the riders affected on the K, L and M light-rail lines, according to Muni chief Nathaniel Ford. Muni carries about 700,000 passengers daily and Ford said the outage impacted 250,000 riders.
Service was restored by 7:15 p.m., Muni spokesman Judson True said. The delay was caused by the struggle to put the 40-ton vehicle back onto the tracks, said Ford, who had spent a majority of the day in the tunnel with workers assessing the problem. He said the tight space in the tunnel — mere inches between the train and the tunnel wall — left little margin for error while using jacks to hoist the vehicle back onto the track, which was finished at about 5 p.m.
“There’s no room for error,” Ford said. “We want to make sure we’re not endangering our workers.”
The derailment is the fourth in the Muni subway tunnels during the last 3½ years, Ford said. In August 2006, a derailment occurred in the Twin Peaks Tunnel, and that problem was attributed to a flaw with the tracks. Those tracks were soon replaced — including the section where Tuesday’s derailment occurred, Ford said.
True said that the accident occurred while passing a curve in the tunnel. As per normal operating procedures, the train was travelling in automatic mode, meaning the operator was not controlling the vehicle’s speed. Trains typically travel at 27 miles per hour at the site of derailment, True said.
The operator of the train is not likely responsible for any part of the accident because the train is fully automated in that part of the tunnel, True said.
The tunnel itself was constructed in 1917 and the train counted among the “modern, state-of-the-art” cars that began appearing on the rails in the mid-1990s, True said.
During the morning commute, many confused passengers crammed into the crowded shuttle buses, which took considerably longer than the normal light-rail service.
“It took me an hour to get from West Portal to downtown this morning,” said Mimi Wekselblatt, who lives on Ulloa Street. “Usually it takes me about 20 minutes.”
By the evening, Muni had placed workers in each station to explain the shuttle system put in place to transport them, but in the morning, passengers taking Muni from the outer neighborhoods to downtown had little information about what happened.
A crowd of stranded commuters waits near the West Portal station for a bus after a Muni train derailed in the tunnel on Tuesday morning.
Recent high-profile incidents involving Muni vehicles:
Tuesday: No one injured when second car of L-Taraval slides off the track.
Aug. 3, 2009: Six people are injured when two F-Market streetcars sandwich an SUV at Market and Noe streets.
July 18, 2009: 47 people are injured when L-Taraval and K-Ingleside light-rail vehicles collide at West Portal station.
May 26, 2009: 30 people are injured when a 71-Haight-Noriega bus crashes into a car at Market and Jones streets.
June 14, 2008: 16 people are injured when a T-Third light-rail vehicle rear-ends a stopped N-Judah at Fourth and King streets.
Aug. 4, 2008: 14 people are injured when two F-Market streetcars smash into each other on The Embarcadero.