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From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: EZ Pass scanners used on local roads to track vehicles
Date: Wed, 06 Feb 2008 09:38:24 -0500
Message-ID: <>

On Wed, 6 Feb 2008 08:30:48 -0500, "Tomes" <> wrote:

>Here in NJ they seem to opt for under the road magnetic flux counters.  They
>are popping up (or is it popping down?) everywhere now.  They scrape off a
>few inches off of about 50 feet of road, set in the loop wire, and pave it
>over again so if you do not know it is there you would likely not notice it
>(I am the only one who seems to see these things in my family...).  They put
>in a series of three or four in a row in each lane that counts the number
>and speed of the vehicles as they pass over.  I have not noticed any of the
>radar based ones yet here; I suppose the NJDOT has settled on using this

Those loops are the standard "old" technology.  They seem to be pretty much
everywhere and date back to at least the 70s.  I recall stopping once when I saw a
worker doing something inside a cabinet.  I wanted to see what was inside.  There
were a couple of rows of mechanical counters, one for each MPH increment (5mph, I
think.)  This was back in the 70s.  Now it's all digital, of course.

The radar units are rapidly replacing the loops, if for no other reason than the very
intense marketing by EIS.  There are some real advantages.  No pavement to cut, no
wires to maintain and no loops to replace after a paving job.  OTOH, the accuracy
spec of the unit isn't all that hot and given the very bad geometery involved, I'd
have to see the spec proven to really trust it.

Some places are going reaaallly overboard with the things. Along I-75 north of
Cleveland in the fog zone, for instance, there is one every couple hundred yards.  I
notice 'em in many Southern stages as frequent as several a mile.  Atlanta is a very
high density location.  I guess when you're spending other peoples' money...


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: EZ Pass scanners used on local roads to track vehicles
Date: Wed, 06 Feb 2008 16:30:22 -0500
Message-ID: <>

On Wed, 6 Feb 2008 12:47:42 -0500, "Tomes" <> wrote:

>I will now start looking for these things.  What I do see here in NJ are
>'cameras' perched on traffic lights, presumably for the similar purpose of
>intelligent traffic light control.  Why NJ would use these for traffic
>lights yet not for speed monitoring (as i see them installing further loops
>in roadbeds these days as well here) I don't know.   It has spurned an
>uproar of protest regarding privacy around here.  "It is a camera that might
>be taking my picture and recording where I am or whether I ran that red
>lightt."  It is an interesting argument.  While I do not believe that they
>are being used as such, perhaps in the future they could be.  Then they will
>always know where we are when they have enough of these out there.

If there is a camera above each bank of lights with one pointing in all 4 (or however
many roads converge) directions, then they are almost surely being used to replace
the loops for intelligent traffic control.  So far, according to a traffic engineer
friend of mine, they are far more reliable than the loops and don't have any problem
detecting small vehicles such as motorcycles.  My old home town of Cleveland, TN
started a trial of the system about 3 years ago.  It worked so well that they're
going pell mell to replace all the loops with cameras.

AS for surveillance, ahem, some folks need to get a grip. And maybe study some
optics.  I'm as strong a privacy advocate as there is out there but I also know that
it is physically impossible for a stationary camera mounted that far away from the
roadway to record much of anything other than general vehicle shape and color.  That
would hold true even if the camera were high-def, which the cameras in question
certainly are not.

Take a look at the camera systems used for toll and red light enforcement to see just
what it takes to record a tag and a face.  High res camera, either flash or high
intensity illumination, tightly focused telephoto lens, sometimes several cameras and
most importantly, a precision trigger signal that will fire the shutter when the
vehicle is in a precisely defined location.


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: EZ Pass scanners used on local roads to track vehicles
Date: Wed, 06 Feb 2008 20:18:15 -0500
Message-ID: <>

On Wed, 6 Feb 2008 18:08:32 -0600, (Kenn Smith) wrote:

>I have viewed the shots from a local red light camera.  No way can you
>make out a face.  You get a general shot of mostly the rear half of an
>automobile and a license plate.

The red light camera that Cleveland evaluated shot the front and rear licence tag
location (TN only uses rear tags) and a fairly close-up shot of the driver's face.
Most modern ones do that, the result of successful court challenges to these
machine-issued tickets where the car owner claimed not to be driving.

This system had the cameras mounted at about the 10 ft level.  Several cameras in
each pod, two pods per direction.  Positional triggering was done with video, a feed
from the same camera that operates the intelligent light.  That camera feed is ONLY
for position detection and not part of the ticketing mechanism.

If you google around you can find example photo tickets that show nice above the
shoulder "portrait"s of "violators".

In a rare moment of collective wisdom that made me kinda proud, the citizenry
revolted against these cameras.  The result was that they got yanked after the trial
period.  The only thing that surprised me about the whole ordeal was that the cameras
lasted long enough to actually be yanked.  I'd have figured them for dying of lead


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: EZ Pass scanners used on local roads to track vehicles
Date: Fri, 08 Feb 2008 08:23:21 -0500
Message-ID: <>

On Thu, 7 Feb 2008 22:42:26 -0500, "Tomes" <> wrote:

>Thanks John and pretty much agreed here.
>One last thing that I noticed is that the loops are on the state roads only
>and the cameras are only on the county roads.  I am guessing that there is
>more inertia on the state level from this.

You're welcome.  I forgot to add to the previous post.  On the system that I got to
look over the shoulder of traffic engineer, the programming laptop displayed a full
screen image from each camera.  The camera was positioned to see part of the
intersection and perhaps 8-10 car lengths back up the approaching lane.

The engineer drew in detection zones in each lane.  Each zone is the roughly the
length of a car and spans the lane.  If anything rapidly changes (there is a rate
threshold so that the detection algorithm doesn't respond to time of day, clouds
passing by and so on) in the zone then the system registers a vehicle being present.
This is just like how video-based security motion detectors work.  The sensitivity
can be programmed and it is generally set to detect something as small as a
pedestrian or bicyclist.

From the vantage point of the camera, all that is visible is, essentially, the tops
of cars and reflections from the windshields.  I looked closely because I am
concerned about the surveillance abuse potential, and could not even discern human
outlines behind the windshields, much less faces.  Even absent the windshield
reflections, at most, vague outlines would be visible through the glass at that
distance. And of course, since this system faces against the traffic, not even the
outlines of any tags were visible.

For reasons that I don't fully understand, the traffic engineering and management
community is, well I can't say secretive because I've never had a question refused an
answer, insular.  They don't seem to communicate outside their discipline.  That's
unfortunate, because some information would go a long ways towards defusing the sorts
of conspiracy theories as you've heard.  That would leave time for us to worry about
the REAL conspiracies :-)


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