Railway Corridor (landuse=railway) is used to tag areas of railway land:
It’s not clear where the boundary should be placed. Does this cover only the formation, i.e. the area of compacted ground on which the tracks are laid, and associated buildings and infrastructure?
Or does it extend to the boundary fence of railway-owned land? In the UK all railways are fenced by law and it is a serious offence to trespass on railway land, so the boundary needs to be clearly marked.
There is often a very big difference between the width of the formation, and the area within the boundary fence. For example in a cutting the railway fence runs along the top of the cutting. On an embankment the railway fence runs along the base of the embankment.
The sides of cuttings and embankments are often quite wide and mappable in their own right as grass, wood, scrub, etc., so mapping them as railway corridor looks odd.