News and Reaction, Technology

West Portal Collision

This past Saturday one Muni train rear-ended another at the West Portal station, half a mile from my house. I decided to stay away from the scene, so as not to crowd an accident scene where authorities were attending to around fifty injuries.

I have ridden these trains a great deal. They run under computer control through the subway and then convert to manually-operated streetcar service at West Portal station. Apparently, after switching to manual control at West Portal station, the driver blacked out, so his train rolled down the track at 20-23 MPH, colliding with the train in front of it.

The Chronicle points out that there is a consideration of the practice that Muni has been allowing trains to switch out of automatic mode in the tunnel before entering West Portal station: by overriding the computer control, a second train can get in to the station platform, allowing passengers a chance to change trains. Had this train remained on automatic, it would not have been allowed into the station, and the accident would not have happened.

But, to me, the thought of switching to manual control early doesn’t sound like the problem. The problem appears to be that the driver blacked out while operating a train, possibly due to a diabetic condition. In this case it may have been a blessing that he blacked out at West Portal, where his train was stopped by the train before it. Had he blacked out outbound of west Portal, his L train could well have been rolling downhill on Taraval across 19th Avenue, with little more substantial than automobiles and pedestrians to slow its descent.

I spent a little time researching whether the Breda vehicles are equipped with a dead-man’s switch or not, but couldn’t find anything conclusive. I found some reference to dead-man’s switches being required on all vehicles after 2000, while the Bredas were introduced from 1995 to 2003. My hunch is that there is a dead-man’s switch or other vigilance device, but it may not kick in automatically: had the train been rolling down Taraval maybe the brakes would have kicked, but a few seconds pulling up to the platform at West Portal was enough time for an accident between vehicles operating with minimal distance.

I don’t know . . . NTSB gets to figure it all out. I’m just glad nobody got killed.

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Categories: News and Reaction, Technology