No #hit sherlock.
I can give you a perfect example of how they are NOT and how there is nothing that can be done about it short of profiling and checking every commuter's bag:
I ride New Jersey Transit into Penn Station every day. There are dozens of NJ Transit commuter trains running on many different lines throughout the state serving thousands of commuters every day. A potential suicide bomber equipped with a cell phone device get on the train at any one of these New Jersey stations, take the ride into NYC and detonate as the train enters the NYC tunnel below Penn Station. They can have a thousand guards and officers inside Penn Station itself, but it will do no good whatsoever in stopping them from coming INTO the station from New Jersey, or Long Island for that matter. I'm always on the lookout to see who gets on as the train pulls into those stations that have a large ME population.
Good thing I wasn't drinking anything when I read your post or I'd have spit it all over my keyboard ***smiles****