🚀 go-pugleaf

In article <BzGzsI.1u4@chinet.chi.il.us> drx@chinet.chi.il.us (Scott Whittle) writes:
>Ok I'll bite.  How does the railroad control the crossing gates?  Here in
>Illinois, Chicago and NorthWestern changed over the technology at the
>crossings about 2 years ago and have had major problems ever since.  Gates


The old style worked by detecting a short circuit between the rails 
(a locomotive is pretty conductive). If you walk the track near a
crossing and pay attention to where the rail ends meet, you will see
that some are electrically connected and some are isolated. You will
also find cables connected to the rails running under-ground toward
a nearby electrical box which controls the whole thing.

I have been told (but have not seen) that there are two systems used
now-a-days. One is a load sensing system where load cells are placed
on the rail and detect the weight of the train. The other is inductive
similar to the loops which control automotive intersections.

John 
(My brother in law drives big trains for a living)



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