Ergonomics In The Mainstream Media: Improper Shift Schedules And Train Collisions

I don't know if anybody out there in Canada caught this last weekend, but on Discovery Channel's Mayday: Head-On Collision, they profiled the factors behind the cause of the Hinton Train Collision. In 1986, trains that would normally pass by each other on separate pieces of track ended up, through a tragic series of errors, on the same rail, and smashed into one another at top speed. 23 people were killed, and scores of other passengers on the train were seriously injured.

Alison Smiley of Human Factors North served as an ergonomics expert at the subsequent inquiry into the disaster, and lent her voice to the television special, appearing for a 10 minute segment on the ergonomic aspects surrounding that tragic day.

Despite the fact that warning lights told the conductor of the freight train to stop, the train sped on unimpeded. Why did this come to pass? According to the program, the train conductors were very tired on the day of the incident, getting 5 hours of sleep or less. The collective fatigue of the freight train crew may have caught up with them, as a combination of being asleep on the job led to signals not being sighted and a rigged deadman's pedal kept the freight train on schedule to reach its final, horrific destination.

Why were the conductors getting so little sleep? Why was the Deadman's Pedal rigged with a lunchbox? The conductors got little sleep frequently because when they were working, they were on call 24 hours a day, 7 days a week. Not being able to settle into a pattern of wakeful alertness and sleep, their circadian rhythms were messed up, resulting in low energy levels when awake, as the body thought it should be sleeping when it wasn't. As for the Deadman's Pedal, it was rigged because in order for it to function as intended, the operator would have to keep the pedal depressed for the vast majority of the time in order for the train to run (taking the foot off triggers an alarm fairly shortly afterwards, shutting the train off briefly after that). As it is fatiguing to do this for hours at a time, they rigged the switch so that they could drive the train in comfort.

A perfect storm of these extenuating factors led to the train collision, a day of infamy in the history of Canada. Nowadays, CN has a anti-fatigue system that has been lauded by other in the railway industry, and the Deadman's Pedal has been replaced by pressing a sequence of controls regularly, freeing up the foot from that duty.

Indeed, ergonomics can mean the difference between a MSD and good health, or between a catastrophic disaster and getting home safely.