Walking along the former wabash main here, I recently noticed short sections of rail near gated crossings had been spray painted blue, and had sensor wires of some sort running into a plate shaped box mounted between the rails…
Stenciled on each of the several plates located nearby (multiple crossings) was what appeared to be long wave radio frequencies, such as “280 Hz Ross Avenue” or “318 Hz Smith Rd”…and a quick inspection showed that each cross road had it’s own frequency.
I suspect this to be a fairly recent installation, since the paint and all were so sparkling new looking, and the dudes in the white trucks were just out there the day before working on the rails and gate control cabinets.
Well, I was just a casual observer, sitting back and watching a few freights,…until I noticed the gates triggering for no reason,…not once,…not twice, but 3 times within a 10 minute period…
Stopping quite a few cars in the process…
Are these new gate controls that prone to “falsing”?
The technology has been around for years. Saw it described once in Trains relative to cab signals. I’m not a signal maintainer, but the problem is either the teething that Huge alludes to, or changes in the roadbed. Salt + water increases conductivity, which can cause false trips. As I recall its a problem the signal folks fight all the time, getting the sensitivity balanced between properly sensing trains and not reacting to the conductivity of the roadbed.
The frequencies aren’t even RF - they are actually in the audio range (Middle C is around 260 or so). While electronics are used now, at one time all that pulsing was done by relays…
Yeah, all the rail was welded, and since there were 2 rail lines crossing each other with near by grade crossings in 3 of the possible 4 directions, all of the switches between the lines had wire jumpers spliced in, patching around the switches