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From: bc338569@longs.LANCE.ColoState.Edu (Brian Catlin)
Newsgroups: sci.electronics
Subject: Re: IR receiver on traffic lights ?
Message-ID: <14166@ccncsu.ColoState.EDU>
Date: 12 Apr 91 02:03:53 GMT
References: <1991Apr11.211957.7309@lynx.CS.ORST.EDU>
Sender: news@ccncsu.ColoState.EDU
Reply-To: bc338569@longs.LANCE.ColoState.Edu.UUCP (Brian Catlin)
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Organization: Engineering College, Colorado State U.  Ft. Collins, CO  80523
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In article <1991Apr11.211957.7309@lynx.CS.ORST.EDU> youngqd@jacobs.cs.orst.edu (Dean Youngquist) writes:
>The fire trucks in my town seem to trip traffic lights to green in
>their direction as they are approaching the intersection.  Does anyone
>know how they do this?

Here they use radar detectors mounted on the wire or pole that the stoplights
are on.  There are two sets per intersection.  One points North and South while
the other one points East and West.  Fire trucks and police can both trip these
but the computer sometimes screws up and turns all four directions green!
This can be quite confusing :-)

If you see radar guns mounted on the fire trucks then that's how they probably
do it.  Police just have to point their guns up so that there is a straight
path to the detectors when they want to change the lights quickly.  This is
done very infrequently since it confuses the computers so much.

Hope this helps!

B. J. Catlin

bc338569@longs.lance.colostate.edu