gatefive:Have you looked at the Atlas system. They have detectors setup for DC, but you still have to divide the
mainline into a number of blocks to isolate each train. Nothing in signals or block detection is really cheap but this is fairly low cost and it works right out of the box.
Dick Foster
that actually looks pretty close to what i'd like to do. i can't tell, though, from their page, if it just controls the signal aspects, or includes stopping locos, etc...