Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!sdd.hp.com!spool.mu.edu!cs.umn.edu!uc!shamash!timbuk!willow23!rice From: rice@willow23.cray.com (Jonathan Rice) Newsgroups: sci.electronics Subject: Re: Traffic signals Message-ID: <111016.10481@timbuk.cray.com> Date: 22 Apr 91 17:04:25 GMT Article-I.D.: timbuk.111016.10481 References: Distribution: usa Organization: Cray Research, Inc., Eagan, MN Lines: 21 In article lrk@k5qwb.lonestar.org (Lyn R. Kennedy) writes: > The Opticon units installed around here force the signal green >to clear out traffic. The red-all-directions scheme has a safety >fault: If it doesn't work, the emergency equipment may be racing >into an intersection while the cross-traffic has a green light and >the driver thinks it's red. 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. -- Jonathan C. Rice | Internet: rice@cray.com | UUCP: uunet!cray!rice