1. A delay can be built into the circuit or into computer logic down-
stream of the detector to hold the indication for a time to allow
the next car to move into position. When the train has finally
passed, this delay will time-out and give the clear indication.
2. A strictly mechanical method to address the problem is indi-
cated in [1-B]. The source/detector pair is set across the rails at
an angle such that the largest gap between cars will not expose
the detector. Setting up the source/detector pairs in this way
avoids any further electronic or software complications.
2
2. The Ambient Light Optical Train Detector.
Optical Train Detection - 3
Aiming an interrupter detector can sometimes be a problem,
especially with LEDs which can have a narrow beam. But this
problem can be overcome.
A somewhat thornier issue is how to scenically camouflage all
of the line-side light sources and light detectors. Some can be
hidden behind relay cabinets, bushes, sheds, signs, etc.
But after some number have been hidden, the layout might
become cartoonish for all of the clutter beside the track.
The problem is compounded if double or triple track has to be
detected separately. All of these limitations can be overcome
MRH-May 2014
