Jehovah Witness literature at the Houston Metro Park & Ride station

I take the Houston Metro Park & Ride bus to work. At the station I use the Jehovah Witnesses maintain a stand with their Christian literature for people to take.

Is this legal? Does Metro condone religious groups handing out literature at their park and ride locations? Can any business, politician, or religion advertise at the park & ride locations?

Personally I believe in separation of church and state and don't think Houston Metro should allow this sort of literature on its properties.. but I'm afraid if I raise a fuss then I could be subject to retaliation.

Does your park and ride location have this sort of religious literature being handed out? How should I respond?

Thanks, cheers