On Monday morning a 3-Jackson bus ran into the back of a parked delivery truck, damaging both vehicles and injuring the driver and two others. According to a leaked memo obtained by the Examiner, SFMTA officials believe the crash was caused by a computer error aboard the Muni bus. However, while the cause of Monday's wreck appears to be unique, other braking problems identified by Muni drivers could be widespread.

The results of a preliminary investigation, shared with Mayor Ed Lee, suggest that the driver applied both the brakes and the parking brake before colliding with the specialty food delivery vehicle. Neither brake, however, worked to stop the bus in time. And that, according to the memo written by SFMTA Director of Transit John Haley, is because a computer error prevented them from doing so.

“When the operator applied the foot brake, the computer should have signaled the traction motor to decelerate,” writes Haley. “It did not. When the parking brake valve was activated, it too should have signaled the traction motor to reduce power."

“That communication link also failed,” he continued.

While officials claim Monday's problem is a unique one, Muni drivers that spoke with the Ex confirmed they too had experienced a glitch that hindered their ability to brake while operating a specific type of Muni bus — the Electric Transit Inc. vehicles that use trolley poles to connect to overhead wires. Early reports indicate that the ETI buses are going into "restrictive mode," a mode used for testing, and that steering and brakes are both impacted when this happens.

There are 273 ETI buses in the fleet, and SFMTA officials confirmed to the paper that "ETI buses across the fleet enter restrictive mode about once a day."

“It’s imperative when that happens you do the best you can to stop immediately," one driver told the Examiner. "You lose steering. I’ve been driving down the street, and it goes into restrictive mode. That’s happened to me at least 10 times."

"Anytime it stops, it’s a danger for you and your passengers,” the driver concluded.

Previously: Muni Bus Collides With Parked Truck, Catches Fire, Injuries Reported