Red light district

The thought occurs, why is it that railway accidents, some of them horrific, are often due to signal failures (alarming when it apparently takes 1 1/4-miles for a 100mph train to pull up) when the red, amber and green traffic-lights that safeguard road-crossing seem to be extremely reliable?

Although the two towns nearest to where I live in Wales have no such red lights (yet), I do motor further afield, and from observation would think that road-system traffic lights are extremely reliable (casual contractors’ ones are in a somewhat different category) and presumably have a fail-safe system so that the “go” light cannot show in two directions at the same time. I deduce the reliability factor from the infrequent times one sees anyone carrying out servicing of these electrical point-duty lights, failure of which seems to be mostly only a case of a general power-cut. One thing we can rejoice about!