----- Original Message ----- > From: "Brett Frankenberger" <rbf+na...@panix.com>
> The typical implementation in a modern controller is to have a separate > conflict monitor unit that will detect when conflicting greens (for > example) are displayed, and trigger a (also separate) flasher unit that > will cause the signal to display a flashing red in all directions > (sometimes flashing yellow for one higher volume route). > > So the controller would output conflicting greens if it failed or was > misprogrammed, but the conflict monitor would detect that and restore > the signal to a safe (albeit flashing, rather than normal operation) > state. "... assuming the *conflict monitor* hasn't itself failed." There, FTFY. Moron designers. Cheers, -- jra -- Jay R. Ashworth Baylink j...@baylink.com Designer The Things I Think RFC 2100 Ashworth & Associates http://baylink.pitas.com 2000 Land Rover DII St Petersburg FL USA http://photo.imageinc.us +1 727 647 1274