I don't think it violates the Constitution, nor do I think it allows for warrantless searches of private domiciles.

They are referring to structures and/or land that is "adjacent" to the rail structure for purposes of safety. For instance, they could become aware of a terrorist attack plot involving planting explosives in a building or other structure that is directly adjacent to the rail structure in an effort to sabotage the rail system.

It would be necessary to act immediately on this type of intelligence and not wait for a warrant in order to save lives.

I'm not one to put my trust in the government, but I also don't see conspiracies and infringements on my rights where there simply aren't any.