- “Down means 'go', and up means 'stop'. So upper still must mean 'go back'!”
In terms of running railways, signals are mechanical and electrical devices erected beside a railway to pass information relating to the state of the line ahead of the engine.
Signalmen use these to direct an engine's crew to make certain movements or to stop from their signal boxes. However, sometimes either the signalmen or the engines do not pay attention, often resulting in accidents.
On Sodor, all signals point upward to indicate that an engine needs to stop and downward to indicate "go". Gordon and James once played a trick on Percy about "backing signals". So when Percy came to a signal and it went up instead of down to indicate that he could go, he thought it was a "backing signal". Toby was once baffled by the large gantry at Knapford. James also accidentally knocked down two signals, once with some well wagons of tractors, and another with Rocky's crane arm causing confusion and delay. However, in recent episodes, the signal for "go" has changed back to downwards.
- Railway Sidings
- Gordon's Hill
- Shunting Yards
- Signal Boxes
- Quarries and Mines
- The Coaling Plant
- Crocks Scrap Yard
- Level Crossings
- The Intersection
- The Branch Lines
- The Main Line
- The Great Railway Show Yard (Mainland)
- Since the thirteenth series, signals have a different sound when changing.
- The signals on Sodor are old-fashioned, semaphore railway signals, still used in some countries today, mostly in the United Kingdom. They are also found on vintage railways and railway museums that preserve both steam and diesel locomotives as historical pieces, such as the Illinois Railway Museum in the United States.
- Throughout the television series, some of the signals are incorrectly shown with the coloured side pointing to the left and the black and white side pointing to the right. Also, the yellow arm distant signals all have a red light on them. But in real life, they only have a yellow/amber light.
- ERTL (discontinued)
- Wooden Railway (multiple versions, all discontinued)
- Motor Road and Rail (discontinued outside of Asia)
- TrackMaster (discontinued)
- Hornby (discontinued)
- Bachmann (discontinued)
- Capsule Plarail
- Mini Mini Plarail (discontinued)
- Railway signals and their descriptions from The Signal Box.