Open Train Times Website

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Permalink Reply by Glenn Wallis on June 29, 2013 at 13:52

This is quite amazing. What you can see is exactly (more or less) what the 'signaller' (hate that word!) can see in his signal box or the what appears on the controller's screens in the control office.

 

How is this info generated, you ask? Surely it must be through GPS technology or something similar? Nope! It's all thanks to an early 20th century safety device to detect and protect trains through interlocking with the signalling system - the track circuit. Dead simple, a weak electric current is passed down an insulated, electrically isolated section of running rail. When a train passes over it the current is short circuited by running through the axles to opposite running rail, causing an electrical relay to drop and indicating the train's presence. That simple idea has been steadily developed over the last hundred years so that the trains can operate the signalling on simple bits of railway themselves and through the train describer system drive the Customer Information Systems on stations as well as the signaller's and controllers displays.

 

Each train has a 4-character identity generally called the 'headcode', because years ago the code was carried on the front of the train.

 

First character: 1 = Express Passenger; 2 = Ordinary Passenger; 3 =a few special track maintenance trains; 4 = 'freightliner' and similar fast (75mph) freight trains; 5 = Empty Coaching stock; 6 = 60mph freight trains; 7 = 45mph freight trains; 8 = 35 mph freight trains (not many of these, these days); 9 = used to be for freights that ran below 35mph without continous brakes, they were finally abolished in the late 1990s, now used for Eurostar, East London Line and late running trains being excluded from the performance statistics; 0 = locomotives running on their own.

 

Second character: Destination letter. On 'inter-regional' trains: E = Eastern; L = Anglia; M = London Midland = O = Southern; S = Scottish; V = Western; X = Out of gauge load; Z = Inter Regional Special. Each region has its own group of destination letters for destinations within its own region, eg 'J' for Barking - Gospel Oak passenger trains.

 

Here endeth today's lesson!

 

Glenn

 

Third & fourth characters are the train's number. At only two characters, the number cannot be unique to the train but couple with the Class number and destination letter, the timetable planners try to make sure that two trains with the same headcode are not running at the same time in the same part of the country.

Permalink Reply by Stephen Middleton on June 29, 2013 at 18:53

Thanks a lot for explaining all that, Glenn.