For Railwaymen Red means Danger. The Red light at the rear of the train tells the signalman that a train that has passed his box is complete and has not become separated along the way. The Red light on the signal tells the driver he must go no further for fear of an accident.
In 1876 a terrible accident at Abbotts Ripton involving three trains resulted in far reaching changes to the way that British Railway signalling operated. In a driving blizzard, snow prevented signals that showed as clear to the driver from being pulled to danger and the southbound Flying Scotsman collided with a freight train that was reversing to get out of its way. A northbound Leeds express – ironically running to time in the terrible conditions – then ploughed into the wreckage. Fourteen people lost their lives.
The crucial change made was that all signals should by default show Red for Danger rather than clear and that they should always be visible. The most obvious example of the fallout from this accident on Britain’s Railways today is that the Red light is at the bottom of the colour light signals where it cannot be obscured by snow piling up on the hood of a light below. Simple but so very important…
For those who would like to read more about railway accidents and how the investigation into their causes is used to promote improved rail safety, I recommend Red For Danger by L.T.C.Rolt.