ION - Waterloo Region's Light Rail Transit

[trainspotter139]

I read an article which said that any train with a door that wouldn’t close would be locked out by the ATP (automatic train protection) and could only be moved under old-school procedures essentially involving written authorization to use sections of track.

Total engineering fail; ATP has no business absolutely preventing a train from operating just because of door problems. There should be a procedure to inform the system that the door has failed, possibly install a temporary barrier, and continue on, even in service if appropriate.

What horrors lurk in the design away from areas where I can confidently assert the designers screwed up?

I hope this isn’t the way of the future: software industry practices applied to other industries. By this I mean products which, while technically meeting the spec, fail to operate in the way which anybody who actually thought about the problem for a few minutes would realize they should operate. The customer should not be responsible for thinking of all the obvious, goes-without-saying, features and putting them explicitly in the spec.

1. I think you are mixing up ATP with ATC. ATP is just a signaling system that compares train speed with permitted speed and signals the train control computer for brake activation if the train speed is above the permitted speed. ATC takes control over acceleration and braking and works in conjunction with ATP to operate the train safely.

2. That's not an engineering fail at all. All modern passenger trains have a door interlock braking system. When the doors are open, the brakes are activated. When the doors close properly the brakes are then deactivated. If the doors do not close properly, the door interlock brake stays active. ATC is a completely separate hardware module that simply sends commands to and receives data inputs from the train control computer. ATC doesn't get a signal as to why the brakes are active. All ATC gets from the train control computer is basically: "Brakes: Active, Position: Service-50%, Locked: True". ATC would operate in the same fashion if the operator hit the emergency stop switch on the control panel. All ATC would know from that is: "Brakes: Active, Position: Emergency, Locked: True". ATC can only control the train if the controls aren't locked out by another module with higher control priority, like the emergency stop switch or door interlock brake.