Something that will need to be decided early on in the construction of your railway is how you plan to power it.
In the garden, power may create additional problems that it would not cause on an indoor layout.
Electric Track Power
Generally, this is how an indoor layout will be powered. In the garden, dirt (or even insects) may get on to the track which can disrupt the power supply. Regular maintainance of the track is essential if you use this method of power.
Many garden railway owners prefer live steam – it adds realism to any railway – and it’s fun!
This can be more expensive, and is a little more difficult to run, but that will pay off in the enjoyment you will get when running your trains.
Generally this is only viable for larger scales, but batteries may be placed inside your locomotives. This is probably the easiest option (in terms of initial construction and running costs too).