Monday's violent accident at the Chicago Transit Authority's Blue Line station at O'Hare raises new questions about whether the transit system's own automated safety systems are adequate to prevent accidents when the motorman fails to keep the train under control.
Investigators cautioned Monday that nothing is certain and that the probe into the accident will take months to complete. But even the president of the CTA union said it appeared the motorman had dozed off at the controls. Certain systems are designed to take control of the train if the person driving it isn't obeying proper signals. It isn't clear what happened at O'Hare on Monday.
"From what I've seen, this looks like the perfect storm," said Amalgamated Transit Union president Robert Kelly. "Lined up perfectly!"
Kelly said the motorman had a year's experience at the CTA, and in this particular case had about 17 hours off before beginning her shift at about 8:40 Sunday night.
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"She has assured me there is no problem with her passing the drug and alcohol test, so that is not a factor in this," Kelly said. "She said she was extremely tired. I didn't go into an in depth conversation with her, but it has been reported that she nodded off."
There are at least two primary systems which are on the radar of investigators. First and foremost is what is known as the "dead man's switch." The train is driven by the motorman with his or her hand on a tiller known as a "Cineston controller." If that handle is released for any reason (for example, if the motorman falls asleep or has a heart attack), the throttle is cut, the brakes are applied, and the train comes to an immediate stop.
That didn't happen here.
A second system is called Automatic Train Control (ATC). That system works in tandem with speed signals along the route. If the motorman ignores a speed warning or other caution for any reason, ATC will first give an alarm, and if it's ignored will take over and stop the train.
That also did not happen.
"I don't think she was going 80 miles an hour," Kelly said Monday. "It's just unfortunate. And indications are that she might have dozed off."
The speed limit entering the station is 25 miles per hour, and it then immediately goes down to 15. If the motorman was at or below that limit, Kelly noted, nothing in the ATC system would have commanded the train to stop. In other words, it was the motorman's job to stop the train. And if she indeed did doze off, the train would have rammed the post at the end of the platform under power.
Kelly did question why the post at the end of the tracks didn't stop the train, and wondered aloud if it came loose, essentially becoming a ramp which launched the train up onto the platform and up the escalator where it came to rest.
"If you went to CTA or the NTSB they would have said the stuff that's in place should have stopped that train," Kelly said. "Obviously, it didn't. So now we have to find out why it didn't. And how do you change that?"