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From: hodor@hplabsb.UUCP
Newsgroups: net.bicycle
Subject: Re: car-sensors at traffic lights
Message-ID: <3037@hplabsb.UUCP>
Date: Thu, 8-Aug-85 13:46:28 EDT
Article-I.D.: hplabsb.3037
Posted: Thu Aug  8 13:46:28 1985
Date-Received: Mon, 12-Aug-85 22:29:32 EDT
References: <1043@umcp-cs.UUCP>
Distribution: net
Organization: Hewlett Packard Labs, Palo Alto CA
Lines: 27

> What do y'all do when you're stuck at a traffic light that won't turn
> green for you 'till something with enough mass to trip the traffic
> sensor comes along, but there are no cars coming the same direction you
> are?
> -- 
> 					Fred Blonder (301) 454-7690
> 					harpo!seismo!umcp-cs!fred
> 					Fred@Maryland.ARPA

I have been able to trip most car-sensors at traffic lights.  Most of the
new ones are metal detectors.  The problem is to know where to ride to trip
them.  All of the ones that I know of are made by cutting a slot in pavement
and placing a wire in the slot.  The slot is covered by tar.  The pattern of
the tar is the key.  There are two configurations that I know of:
	
	1. The "8" configuration.  This looks like a number 8.  To trip these
	   ride your bike over the center line of the eight.  This is the
	   most sensitive part of the metal detector.
	2. The single "O" configuration.  This configuration is sometimes 
	   the more difficult to trip.  It is usually less sensitive.  If
	   it can be tripped by the bicycle you need to ride over the edge
	   of the circle.  

I hope these hints help.  Happy "tripping."
	
					Ken Hodor
					hplabs!hodor