I'm looking at putting some webcams up to monitor railroad tracks at
various places. Anybody have any good ideas for getting the data
back to the real world?

Second question -
The cameras are usually triggered by home security type IR beam sensors
installed across the tracks, high enough that people don't trip
them. usually the active portion is on the camera housing and
the other end is just a retroreflector.

At least one of these will be mounted on a pedestrian overpass,
directly over the trains. There are 6 tracks going under the
overpass at this point, so the beam needs to be nearly horizontal
to detect them all.

I can't put anything on RR property. It all has to be on the sides or
top.To boot, it all has to be a compact, easy to install unit.

Anybody with a bright idea how to wire this all up without a massive
wire stringing headache?

Oh, the guts of the webcam unit is a PIC, so I'm on topic.