track bikes and liability

A friend of mine shared a Colorado website that offers 4'-8-1/2" track width rail bikes that allow you "a way to reuse abandoned railroad tracks....". The site also proposes a 36" gauge version.

I would guess/assume a track bike would be a nightmare of liability for anyone owning a rail right of way, abandoned or otherwise. Are there places in South America that encourages or allows these track bikes? I've heard of people saying they entertained the idea to do something similar with home made track bikes, but never saw one actually used. I know there is a ton of paperwork in preparation for legalities and safety for these speeder groups to run their equipment on rail lines in the US.

The track bike website does not include instructions as to where to drop off your liability waiver.

Craig