Get On, Clip In, Fall Off

How to be a happy commuter, part 1

I regularly travel to work on the London Underground from Morden station on the Northern Line. Knowing a little about how railways work is sometimes very useful for the stressed commuter, so it's in the spirit of universal harmony that I share this tip.

If you're at a station where trains in the same direction use more than one platform (the most obvious and most usual examples of these are terminal stations) it can often be hard to work out which train is going to go first, especially if you're somewhere like Morden where the passenger information displays often bear no resemblance to reality.

Morden is the southern end of the Northern Line. The station has, effectively, three platforms, and northbound trains can depart from any of these. So how to tell which train's going to go first? The answer is to know your signals.

The signalling system knows better than you do, knows better than the passenger displays, and often knows better than the staff on the platform which train is going to be departing next. If the signal at the end of one the platforms (the station starter) is green, then regardless of what the information screens say it's 99.9% likely that the train in that platform will be the next one to depart.

For reasons of safety which become obvious with a little thought, changing a signal that's signalling a driver to proceed back to danger (i.e. red) in front of a train is a very bad idea and something that is generally only done in an emergency such as an obstruction appearing in front of the train. In these cases the signals will be thrown to red in the hope that the train hasn't passed them yet, but under non-emergency circumstances it's very, very unusual for a signal to change from green to red in front of a train.

Even more usefully, at Morden there are signal repeaters on the platform for those platforms where it's hard to see the aspect of the starter from the platform, so if there are two or three trains in the platform and people are hovering between the two, just check the state of the starter signals and see if one's green. If it is, then that's the train to confidently stride towards (or maybe hurry towards - Underground drivers don't usually hang around long after they get a clear signal, especially at peak times).

I just thought I'd mention this technique as it was of great use to me this morning - the first train to go wasn't the one on the indicator boards, so it departed almost empty apart from myself and a few other fortunate souls while a train that was half-full of people sat idly on the opposite platform, even though according to the indicator it should have been the first to leave. Posted by mpk at February 19, 2004 9:06 PM | TrackBack