Arrows at Terminal Stations

I've always been curious about those arrows that light up under the "Departing" signs in the terminal stations. There is one arrow facing up and one arrow facing the track. I notice that they change each time the train leaves.

Is this to tell the conductor which side of the doors to open first? That's the only thing I can come up with but I doubt that would be necessary.

Anybody know what the purpose of these are? Thanks.

arrow wrote:Is this to tell the conductor which side of the doors to open first? That's the only thing I can come up with but I doubt that would be necessary.

Yes, that's what it is. However, the conductors seem to ignore them at least some of the time. I suspect that may be because by the time they're in a position to see them, they're already located at one set of controls with their key in the panel, and they'd have to close up there and move to the next car to open the other side.