I dunno if this would probably work. The old library of my old school had these big plastic frames (the anti-theft magnetic things). When you stepped on the mat between the two frames you'd hear a "click click" of a counter triggered by a sensor under the piece of rug.
Aside from it making sure you weren't theiving stuff it counted the people that passed through it.
There were two of these things - you went in through one and out through the other.
Considering that you're at a railroad, I'd think a mechanical turnstile, especially a retired one from the NY City Subway, would be quite fitting...
Who remembers the ones with the big horizontal yellow wooden crossbars!!
[This message has been edited by SvenNYC (edited 02-20-2003).]