how do you know what train signals mean?

Question

I often see all these different lights on uk train signals and have no idea what they mean! anyone care to explain?

ie-if you watch british signals there will be two green lights or two amber or one red light second from bottom. Are these specific and why are two shown etc? Wikipedia does not make this clear...

Answer 1

The most simplified version is: (in this order)
Green - Proceed, the next signal will be showing a proceed aspect.
Double Yellow - Preliminary caution, the next signal will be showing a cautionary aspect.
Single Yellow - Caution, be prepared to stop at next signal.
Red - Stop.
Just for info, the yellows are yellow, not amber as in road traffic.

Answer 2

The important thing to remember is that a train can take a long time to stop, since the friction between steel rail and steel wheel is nothing like that between rubber tyre and road. So some form of train control is essential. Every railway line is divided into 'sections'. A section may be many miles or just a few hundred yards. Only one train is allowed on each section at one time.The start of each section is protected by a signal. This is called the home signal. Some way before each home signal is a 'distant' signal. This warns the driver what to expect the home signal to be showing. If the distant is at danger he can therefore slow down ready to stop at the home if that is red. Traditionally signals were simple semaphore arms (with a red or green lamp for night time). Many still are. This means that by each set of signals there is a 'signal box' containing the signaller. His or her job is to regulate the trains using his signals (and change points as necessary). To do this he has pull on a manual lever. He is in contact with the signal boxes either side of his at all times - thus he knows whether or not trains have cleared the section his signals are protecting.
Obviously this is very labour intensive, so most main lines nowadays are controlled by electric colour light signals controlled remotely by a centralised signal box. There is a telephone by each signal though. When a train comes to a stand by an electric signal, after a short time you may notice the driver alight from the cab to speak to the signaller on the phone. This is just to report he is there and possibly find out what the delay is. Afterwards the driver or guard may come on the intercom and announce what the delay is and how long the train will be there. Signals and points are 'interlocked'. This means that a signaller cannot change a set of points allowing one train to cross the path of another without that set of points being protected with a red signal. The British system of signalling has been modified constantly since early Victorian times and is virtually fool proof. The only real danger comes from a driver missing or ignoring a signal at danger. Even here there is an automatic warning in the cab of the train to remind the driver. Often when travelling in the front carriage you will hear a ringing bell. This tells the driver the signal is green. However if it is red or yellow a hooter sounds. The driver has to acknowledge this by pressing a button. If he fails to do so the brakes are automatically applied.
Hope this helps. Though interested in railways I am by no means an expert on signalling!

Answer 3

OK, firstly, the signals are at approx. 1 mile apart - each section of line between them is known as a block and only one train is allowed in each block.

As a train passes a signal, it turns it to red, which means stop. Assuming there are no other trains for at least 3 miles behind, the signals behind also change to double amber (proceed, but next signal is at red), then single amber (proceed with caution) and green (proceed).

Answer 4

They are just like Traffic Lights, Red Stop, Green Go, ah and Amber Proceed with caution.

Answer 5

Well it depends what country you're in.
For instance, in my country, Switzerland the meanings are:
* Green: Proceed at line speed. Expect to find next signal green or yellow.
* Yellow: Prepare for next signal to be at red.
* Red: Stop.
(This is with single lights)
However in the UK you use a double light and so here are their meanings
* Green over Green: continue
* Green over Yellow: caution, next signal at green over red
* Green over Red: caution, next signal at stop
* Red over Red: stop and stay stopped
* Red over Red with small lamp lit: low speed, 25 km/h.

Hope this helps,

Answer 6

Green= go.
single orange=proceed with caution.
double orange=proceed but stop at next signal.
red= stop do not proceed.

Answer 7

Check out this website:

http://www.thortrains.net/handtalk.htm

Hope that helps.

Answer 8

http://en.wikipedia.org/wiki/Train_signals

Answer 9

Sorry , I don't care