Signalling is a complex subject, and it can be difficult for the modeller to get the right 'Look'.
The different railway companies had their own particular designs but in principle a train crew had to carry a train staff, token, or paper ticket given to them by a signalman before their train could proceed onto a single line.
Semaphore signals gave a clear indication that the route ahead was clear for trains to proceed when leaving a station or approaching the next one.
In some situations shunting moves or light engine moves required permission to pass a semaphore signal but not to enter the single line section.
In these cases Ground signals were used to control light engine and shunting moves within station limits.
The Ratio 465 kit allows you to build four disc style ground signals.
A red horizontal bar tells the driver he has to stop
A yellow horizontal bar tells the driver he can proceed with caution. A typical use for Yellow ground signals would be in a yard where the shunts can run up and down a siding, but the yellow disc signal would only be cleared when a set of points was set to rejoin the running line.