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From: jerem@tekgvs.UUCP (Jere Marrs)
Newsgroups: net.cycle
Subject: Re: Smart Traffic Lights?
Message-ID: <1157@tekgvs.UUCP>
Date: Mon, 22-Jul-85 14:11:20 EDT
Article-I.D.: tekgvs.1157
Posted: Mon Jul 22 14:11:20 1985
Date-Received: Thu, 25-Jul-85 03:24:03 EDT
References: <658@ihu1g.UUCP> <2637@ihuxf.UUCP>
Reply-To: jerem@tekgvs.UUCP (Jere Marrs)
Distribution: net
Organization: Tektronix, Beaverton OR
Lines: 52


	The sensors in the pavement work through the perturbing effect
of the magnetic susceptibility of your vehicle on the Q of a high-frequency
resonant circuit. As your machine gets in the vicinity of the wires, it
permeates the magnetic field and changes the inductance of the circuit.
The electronics sense this and detect the presence of the machine. Ferrous
metals are the most effective materials for permeating the field. Size also
affects the field perturbation. Motorcycles are small and their content of
ferrous metals is rather low making it less easy to detect.

	If you can see where the sensor wires are in the pavement, you
can increase the probability of being detected by judicious choice of
position. If the sensor wires are in a diamond shape, place your front
wheel at the top of the diamond and your rear wheel at the bottom. In
other words, straddle the diamond symmetrically. If they have repaved
the road since installing the wires, good luck!

	If the wires are laid out in a large rectangle, try to align
your wheels on top of one of the wires to maximize the effect.

	It *is* possible for them to adjust the detection threshold
such that these measures are unnecessary even for a motorcycle. It
is unlikely, however, that they will attach very much importance to
our problem (my experience in Washington county Oregon). Harangue them.

	I, too, have waited through several cycles of the light to
then run the light as the only alternative. After having been cited for
it, I appeared in court and the judge threw it out of court and
reprimanded the officer. I haven`t been bothered since. I'm sure
that experience is an exception.

	Locally, we have some *new* kind of detectors which, I believe,
are infrared. However they work, they appear to work for motorcycles.

	A new plague for motorcyclists here are the roads that have
been "eaten" by those machines that chomp up the surface for recycling.
The surface is scraped up and trucked off leaving a variable, grooved
surface which is hell on two wheels. The edge is about 1 to 2 inches
high making the exit from freeways so treated a life-risking
experience. They think it is so neat to be able to scrape the old
surface off and then take their time about resurfacing. They regard
the "scraped-off" condition as usable until they`re good and ready
for resurfacing. Around here, that represents months. I am avoiding
most of the freeways for that reason.

	On a positive note, many of the secondary roads are lots of
fun, however.

					Jere M. Marrs
					Tektronix, Inc.
					Beaverton, Oregon 
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