I have yet to find a satisfactory grade crossing for model railroads - they are sometimes done by a physical trigger system on the rails, and occasionally done with optical systems (see link).

By the same token, it's difficult to find a system that can be built into a large-scale model railroad that changes the overhead lights as a train passes under them to add a semblance of realism (real railroad geeks would notice that a light signal on a real railroad changes from green over red to red over red when a train passes below it).

The advent of RFID tags provides a way to solve both problems.

The user places a unique RFID identifier on each car, or simply on the trailing and leading cars (not on the engine, because of the electromagnetic motors that drive the engines). An RFID scanner is placed between the rails at wayside signals and ahead of grade crossings. As the lead car passes over the scanner, the scanner and an associated program tell the lighting systems what to do. The leading car turns on grade crossing lights and bars, or causes the wayside signals to change.

The trailing car turns off the grade crossings, or farther down the track passes a scanner that tells the program, and vicariously the wayside lights, to return to a particular pattern.

Those with the wherewithal to do so could use unique identifier tags for each car, to track their locations.

RFID tags would be applied to the bottoms of cars, probably using some sort of re-usable glue, or could be placed inside the car body (most model railroad cars can be separated into body and base).
-- shapu, Dec 24 2005

Light-based system http://home.cogeco....rpaisley4/GC04.html
Wowzers. [shapu, Dec 24 2005]

You'll have to play with the reader, crippling it, in essence, so that the read distance is very short.
-- bristolz, Dec 25 2005


[bristolz], by not triggering the switch until the signal strength reaches a certain level?
-- Zimmy, Dec 26 2005


I don't think RFID returns anything other than a tag number or a read error.
-- bristolz, Dec 26 2005


So a spinning input wave governor?
-- Zimmy, Dec 26 2005


I just think that you need to somehow make the read distance shorter. If that means a spinning thingy, fine.
-- bristolz, Dec 26 2005


To answer your questions, [half] and [bristolz], each car would be uniquely identified, which I guess I already made clear enough.

When a car which bears the RFID identifier of "lead" or "end" passes over the appropriate reader (which, yes, would have to have a very short effectice distance), then the associated light management program, run off of a laptop or a PDA-like device, would detect that particular car and respond by sending the appropriate command to the lighting system you have set up.

So, it's a multi-part system: RFID -> scanner -> management system -> action of lights

I hope that makes it clearer.

(unrelated note: was this idea not even worthy of being autoboned? AB must be on Christmas break, too)
-- shapu, Dec 26 2005


this can be accomplished cheaper and easier with simple prox switches, RFID is overkill. But, what the hell! It works and its gadgety, have a Railroad-crossed bun.
-- ato_de, Dec 26 2005



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