Newsgroups: sci.electronics
Path: utzoo!utgpu!news-server.csri.toronto.edu!torsqnt!geac!gjetor!adeboer
From: adeboer@gjetor.geac.COM (Anthony DeBoer)
Subject: Re: Traffic signals
Message-ID: <1991Apr25.201250.10438@gjetor.geac.COM>
Organization: Geac J&E Systems Ltd.
References: <N20L11w163w@k5qwb.lonestar.org> <111016.10481@timbuk.cray.com>
Date: Thu, 25 Apr 91 20:12:50 GMT

In article <111016.10481@timbuk.cray.com> rice@willow23.cray.com (Jonathan Rice) writes:
>The gadget in use in St. Paul MN (don't know what brand it is) doesn't just
>switch the colored signals.  In addition, a bright white spotlight, about 1/3
>the diameter of the ordinary colored lenses, goes on in all four directions.
>These lights are mounted on a little mast above the signal.
>
>I had always thought that this was to prevent boneheads from deciding that
>the time was ripe for a right-on-red...but the quoted posting makes me think
>it might also serve as confirmation for the onrushing emergency vehicle.
>
>The scheme has another advantage: I often see the white light before I see
>flashers or hear a siren, and can prepare to pull over.

A third advantage is that it confirms that the emergency-vehicle-detector was
tripped, and makes it a bit more obvious if some bonehead :^) is tripping it
himself with a strobe in order to get to work faster.  If people see the white
lights go on and nothing unusual goes through the intersection, they're going
to start to wonder.
-- 
Anthony DeBoer NAUI#Z8800 | adeboer@gjetor.geac.com   | Programmer (n): One who
Geac J&E Systems Ltd.     | uunet!geac!gjetor!adeboer | makes the lies the 
Toronto, Ontario, Canada  | #include <disclaimer.h>   | salesman told come true.
