Line of least resistance where Moles are the biggest issue might be to dig a few deepish Holes then support Gravel Boards on the resultant Concrete Pads as a new trackbed. Ballast held in place with Postcrete should make a fairly good sweepable track base. This will not stop them but will prevent subsidence as I do not think their holes run too deep. Perhaps an expert could guide us on this?
You're rightThat's 'cos you ain't using it!
Are your buildings resin, or gen-u-wine slate?