Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!sun-barr!cs.utexas.edu!uunet!pilchuck!amc-gw!sigma!bill
From: bill@sigma.UUCP (William Swan)
Newsgroups: sci.electronics
Subject: Re: Car Detectors for Traffic Lights
Message-ID: <2388@sigma.UUCP>
Date: 30 May 89 17:48:45 GMT
References: <18811@cup.portal.com> <3185@kitty.uucp> <456@antares.uucp> <806@ivucsb.sba.ca.us>
Reply-To: bill@sigma.UUCP (William Swan)
Organization: Summation Inc. - Kirkland, Washington
Lines: 34

In article <806@ivucsb.sba.ca.us> ivucsb!todd@anise.acc.com (Todd Day) writes:
}~ I have a related question, can they be activated without the metal mass?
}~The question has probably been asked before, it must be a common problem
}~for urban bicyclists; how do you get the left-turn light to change?
}
}Well, these things must have sensitivity adjustments, because there is
}a set of them on the UCSB campus that controls a bike/car intersection.
}Bikes have no trouble setting off the loops on the bikepath.  The cuts
}in the pavement make me think that the mechanism is no different than
}that used for cars at "real" intersections.

But UCSB/Isla Vista is hardly the world at large. Ten years ago (the last
I could speak for the place), it was *very* heavy in bike riders, and rather
low in auto traffic (most of the time). A special, more sensitive detector
would make a lot of sense there.

Most places there are a lot fewer bikes around, and the sensitivity of
the detectors, whether inherent or setpoint, is a lot lower. To ride out of
my business park, I have to get over to the pedestrian button (on the *left*
side of the intersection as I leave) to get the signal to change.


Now, me, *I've* been thinking about those optical sensors used by emergency
vehicles :-) :-) (Check your local regs first - likely to be quite illegal -
not to mention dangerous if a *real* emergency vehicle is headed towards
the light!! Not to mention  your  legal liabilities in latter case...)



-- 
William Swan  grace.apl.washington.edu!sigma!bill  Send USmail addr for info:
	Innocent but in prison in Washington State for 13.5 years:
	Ms. Debbie Runyan: incarcerated 01/1989, scheduled release 07/2002.
	                   In now:  0 years,  4 months,  1 week,   3 days.