Carolyn
Whether these railways revert back to the original owner depends upon whether the railroads were granted a simple easement or acquired a simple fee title. If the latter, the property owner is probably out of luck.
For those property owners that granted only easement, several years ago the federal court of claims ruled that original owners of railway beds are entitled to compensation plus interest for property taken under rails to trails or similar schemes.
The eco-fascists are trying to snowball people into believing that the local government owns these lands. Several property owners in my area have discovered that they own the property on these rails to trails schemes and have erected fences, keeping the public out until they're paid.
The best thing to do is to hire a good property rights attorney and sue, sue, sue.