Depots
From OpenTTD
See Building Railway Depots for a detailed tutorial on how to build railway depots.
Depots are buildings where trains, road vehicles and ships are built, stored and serviced. Aircraft use hangars which have the same function as a depot but are only available as part of an airport.
Depots have no limit on the size or number of vehicles they can hold at one time. (So they can be used, for example, as Escape depot in front of a railway station)
Depots have a buil-in two way signal (it works as a entry pre-signal in a pre-signal set.)
[edit] Usage
To view inside a depot or a hangar, click on it. You will be presented with a window showing any vehicles in the depot/hangar and also a New Vehicles button to allow you to build ones.
Clicking New Vehicles will present you with a list of available vehicles, which you may then build by clicking Build Vehicle.
[edit] Servicing
Vehicles will periodically return to the depot to be serviced. This restores the reliability rating (preventing them breaking down so often) and prolongs the working life of the vehicle.
You may put a depot on the orders list for a vehicle (in the same way you would a station) to force it to be serviced at a particular point on its journey (for example before a particularly busy station where you definitely don't want it breaking down). And you may use the "service" option on a goto depot order to have the vehicle to execute that order only if it need to be serviced. See Allow goto depot orders page for further informations.
