Crash avoidance?

[mikeb2008]

Hello fellow model railroading fanatics,,,

I'm finally getting back to working on my layout a little, after a long time. I was just thinking of something I'd really like to have... A rear-ender avoidance system of some sort. I tend to like my trains really long, and though I've done a pretty good job making all the rolling stock work well, and get all the track just right, I still once in a while will have a group of cars cut loose. What happens next, if not caught in time, is of course really ugly, when the loco comes around to find it's tail. So I was thinking, something to detect a collission would be really cool. Maybe on the last car that when it detects something behind it, say, within an inch or two, shuts everything down. Has this been done already? I'm an EE 'geek' so I have a couple ideas. Just wondering if it's been done, and looking to kick around some theories.

Mike B, in VA

PS - Heres a look at what I have so far (very EARLY stages). I don't always want to run trains quite that long, but I enjoy the challenge. I know, i know, overkill with the rolling stock, and no scenery yet. I just couldn't wait to get things rolling.

http://www.youtube.com/watch?v=1kxBY6YtOGY

 

[UP2CSX]

Mike, there are a lot of different way you could do this using everything from reed switches to sophisticated optical detection systems. Are you running DC or DCC? If it's DC, it could be something as simple as a reed switch that detects current change in the track ahead although you'd need to figure out how far back you want to stop the following train if the leading train could be long. If it's DCC, current is almost constant so optical detection is probably the best method. There's an old but still good article at http://www.gatewaynmra.org/detection1.htm about block detection that should get your EE juices flowing.