The railway really started in the 16th or 17th century in Europe, if you can consider wagons running on rails in mines to be railways. Pushed manually or drawn by horses, these were the pioneers of railed rolling stock. Moving on in the time, the very early 19th century saw the first locomotives used to move wagons around and soon some clever people started to think about using this has a form of real transport for goods and even people!
Of course, nothing develops without problems and the first accidents, injuries and deaths soon started to happen. So the clever people realised that these heavy trains needed some form of control to try and prevent these accidents and incidents, so along came very crude methods, which they called signalling. As the years went by, the inevitable happened, trains got faster, there were more of them and the methods of signalling had to be improved to cope with the changes.
Improvement was continual, as were the accidents and incidents so signalling rapidly grew to help safeguard the railway. The advent of computers helped make signalling systems smaller in size and faster to operate, with features available that the first signal engineers could never have imagined. Today, signalling has developed to such an extent that safety is ranked as the number one priority in people’s minds when developing the next generation of signalling systems.
Technology doesn’t come cheap and modern signalling uses the most up to date techniques to move those trains about, often at 100’s of km per hour compared to moving the original wagons at walking pace. The signal engineer is often criticised for the cost of signalling systems, the expensive brother in the railway disciplines family, but that cost buys expertise, safety, efficiency, operations and maintenance facilities that would otherwise be difficult to achieve.