costly business building a garden railway! how about this badger proofing? –

“For larger areas, you can prevent badgers digging deep holes by covering the area with tennis-court-type wire netting which is fixed a couple of inches below the lawn surface.

Again the lawn grows through the mesh very well and this is very useful to stop badgers digging under sheds, foundations and buildings. It is a solution used by Badger Consultants who need to protect railway embankments and flood defences against burrowing by badgers, foxes and rabbits.

Again, this is not cheap, but it is a highly effective method to protect areas of vital importance.”

http://www.badgerland.co.uk/help/problems/gardeners.html