The maps show the exact position of trains from the signalling system. The advantage of this over a geographical system is that you can get an idea of where the train is in relation to timing points, and can assess the progress the train is likely to make along the line. In particular you can see other trains which are in the way, loops which may available, whether there is a fast and slow line, and whether another train will be in the way at a junction.
In many areas we are also able to indicate whether the signals the train is approaching are set to red or not, and whether there is a route set for the train across a junction.
Freight lines or loops are sections of track which are normally only accessed by freight trains. These are not always marked separately on the maps, and sometimes appear as normal lines
Points allow trains to converge onto different directions, or converge from different lines
A diamond where two lines cross. Trains cannot switch from one line to another unless indicated in text.
A platform. A number in a white box is the platform number, A red line indicates a walled or fenced-off side.
A signal can be grey, red, yellow or green. Grey indicates that we don't know what aspect is shown. Red indicates that a red aspect is being shown and the driver must stop the train. Green indicates that a non-red aspect is being shown. Depending on the signal in front and the line this may actually be a green, yellow or double-yellow aspect. Yellow signals usually indicate a distant signal where the following signal is set to red.
A solid circle of colour indicates a normal signal. An unfilled circle indicates a shunt signal.
A berth. This is used to show the identity of a train in a particular section of track, or to contain notes set by the signallers. A berth is often attached to a signal. See the codes page for more details of what might be in the berths
Click on this link to follow the line as it continues onto another map