Some information about railroading in the real world, some of it may be useful for use in Railworks too.
Feel free to add more text here, or if it is a longer one to create a new page for it.
Sounding the horn as a warning (US/CAN)[]
Anyone on or near the line
You must sound the horn to warn anyone who is on or near the line on which you are traveling. Give a series of short, urgent blasts of the horn if the person dosen't react immediatly to your first warning.
Whistle Posts
You must sound the horn when passing a whistle post. Trains or engines approaching public highway grade crossings shall sound the horn at least 15 seconds, but no more than 20 seconds before the lead engine enters the crossing. Trains or engines travelling at speeds greater than 45 mph shall begin sounding the horn at or about, but not more than, one-quarter mile (1,320 feet) in advance of the nearest public crossing. Even if the advance warning provided by the horn will be less than 15 seconds in duration. This signal is to be prolonged or repeated until the engine or train occupies the crossing; or, where multiple crossing are involved, until the last crossing is occupied by the train. The horn should be made to sound something in this order: Long, Long, Short, Long untill the crossing is occupied by the train.
Tunnels
All tunnels should have the horn blown on approach in the same order as a railway crossing.
Sounding the horn as a warning (UK)[]
Anyone on or near the line
You must sound the horn to warn anyone who is on or near the line on which you are travelling.
Give a series of short, urgent danger warnings to anyone who is on or dangerously near the line who does not:
acknowledge your warning by raising one arm above the head, or appear to move clear out of the way of the train.
Whistle boards
You must sound the horn when passing a whistle board between 0700 and 2300. You must not sound the horn when passing a whistle board between 2300 and 0700 (except in an emergency or when anyone is seen on or near the line).
Train movements
You must sound the horn:
- when approaching or passing a location where shunting is taking place on a line immediately adjacent to the line you are on.
- At any other time you consider necessary.
Tunnels
You must sound the horn before leaving a tunnel if you see someone on or near the line beyond the tunnel exit.
Other purposes
You must sound the horn on starting your train when:
- Passing a signal at danger.
- Making a movement within a possession. (a section of track under the control of the M-o-W Department that is closed to the normal operation of trains)
Taken from the Network Rail Rulebook, thanks to Dan Dan Dan for posting this on the Steam forums.