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From: larry@kitty.UUCP (Larry Lippman)
Newsgroups: net.analog,net.auto
Subject: Re: Car Detectors
Message-ID: <1021@kitty.UUCP>
Date: Sun, 11-May-86 10:42:39 EDT
Article-I.D.: kitty.1021
Posted: Sun May 11 10:42:39 1986
Date-Received: Wed, 14-May-86 07:05:49 EDT
References: <2974@watvlsi.UUCP> <4839@topaz.RUTGERS.EDU> <992@kitty.UUCP> <986@masscomp.UUCP>
Distribution: net
Organization: Recognition Research Corp., Clarence, NY
Lines: 28
Xref: linus net.analog:801 net.auto:9403
Summary: Detectors measure vehicle speed for "flow control" purposes

In article <986@masscomp.UUCP>, hank@masscomp.UUCP (Hank Cohen) writes:
> 
> I have another question.  I have often seen these detectors placed 
> across the freeway two per lane and I wonder if they are being used
> just to count traffic or does having two separated by a known distance
> allow them to also measure speed.  This could be a means of monitoring
> 55 mph speed limit compliance.

	These detectors are used for vehicle speed monitoring on heavily-
traveled expressways, but NOT for speed law enforcement purposes.  The
detectors are used for traffic control purposes, and information from the
detectors may be used to change the timing on traffic signals admitting
traffic on entrance/exit ramps, etc.  Knowing the average speed of traffic
on a road will also provide advance notice of traffic accidents, vehicle
breakdowns, etc.; obviously if the _normal_ average speed on an expressway
is say, 50 MPH, and all of a sudden it is 5 MPH, that is a pretty good
indication of a problem requiring the attention of police!
	Most major cities have some type of centralized traffic control
center which allows remote control of traffic signals, remote monitoring
of traffic, etc.; such control centers are also found on major bridges
and tunnels.  So, these speed detectors are monitored in those control
center locations.

==>  Larry Lippman @ Recognition Research Corp., Clarence, New York
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