This type of stuff is pretty popular in the US as well. There's lots of videos on youtube of peoples excursions on disused railways, the vehicles are know as 'speeders' in the US, seems to be quite a community of people who are interested in restoring these vehicles and drive them on disused railroads and some companies even arrange for them to be able to travel over operational railways, usually branch lines of some sort.
http://en.wikipedia.org/wiki/Speederedited to add link