April’s Muni Metro mess — which brought the subway system to its knees — was preventable, transit officials said Tuesday.

Muni workers missed a defective part in an inspection that ultimately led to a single train pulling down 1,000 feet of overhead cable wiring, said Julie Kirschbaum, acting director of transit at the San Francisco Municipal Transportation Agency, which runs Muni.

Those inspections are conducted weekly, she told the San Francisco Examiner.

With trains out of service for 13 hours that Friday, SFMTA ran bus shuttles for the roughly 80,000 morning riders of the J, K, L, M, N and T lines. The incident was so severe, and followed so many other high-profile agency stumbles, that it led Mayor London Breed to announce The City should seek a new head of the SFMTA to replace director Ed Reiskin.

In her report on the incident to the SFMTA Board of Directors, at its regular meeting at City Hall on Tuesday, Kirschbaum called the service outage the “worst incident” at Muni she had ever seen.

“We missed something important as part of a routine inspection and it is something we are taking extremely seriously as we move forward,” Kirschbaum told the SFMTA board.

A part called a splice serves as a connector between two pieces of overhead wire, clamping the two together. A “defect on that part,” meaning the splice, contributed to the incident, she said.

“We had warning indications that we could have caught in advance,” she said.

While the defective splice caused the overhead wire to come down, Kirschbaum said the severity of the service outage came down to “bad luck.” In similar incidents, smaller sections of the overhead wires are pulled down, which can lead to short delays. But, Kirschbaum explained to the Examiner, in this particular incident the overhead wire wrapped around the train’s pantograph, essentially the antennae of a train that connects to overhead wires.

With the overhead wires wrapped around the pantograph, the Muni train managed to pull down 1,000 feet of wiring.

“It took two hours just to cut the wires off the pantograph,” Kirschbaum said.

Speaking to the board, Kirschbaum added that the overhead wires are usually dependable and do not traditionally lead to delays on the Muni Metro system.

SFMTA Board of Directors Chair Malcolm Heinicke tasked Kirschbaum with identifying every possible pinch point the subway has that could cripple it.

“I know no one did this on purpose. This should have been prevented,” Heinicke told Kirschbaum. “I apologize to the city. This happened on our watch. It happened on your watch as well.”

joe@sfexaminer.com

Transit