195002 – Riddle – Road Traffic Signalling with Special Reference to Vehicle Actuation

There are not many fundamental principles which are common alike to Road Signalling and Railway Signalling. Indeed beyond the general fact that both are employed for preventing two or more vehicles attempting to occupy the same place at the same time, there is very little similarity. On the other hand many obvious differences present themselves at the outset. The railway signalling scheme can rely upon the trains it controls running upon a pre-set route. The road vehicle cannot (except in rare instances) be directed, but can merely be stopped before crossing a potential collision point. Continuous detection of the presence and passage of a train over a route or through a section is easily provided. The road vehicle can at the best indicate its movement towards a point of intersection by its passage over a detecting device fixed in its path of approach.