perl…@zeno.fit.edu writes:
>We all know of the pressure tubes one ran over in the old (not so old is
it? I
>remember them and I’m only 19!) type gas stations… and they produced a
bell.

>Right?

>Well, why is it that when I’m driving along, I see them placed randomly
along
>certain roads? The lines goto a big metal box on the island… and THERE
IS
>NEVER one tube, they are always laid out in pairs about 2 yards apart…

>HELP! What are these things! They are making me crazy!

I believe they are there to do a traffic count. Certainly here in
Australia that is what they are used for. They  usually appear here when
a re-routing of traffic or other variation of traffic flow is being
considered.

Hope this helps.
Regards,
Peter
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>Excerpts from netnews.rec.autos.driving: 4-Dec-93 Re: "DING DING" THINGS
>IN ROAD by Graham E. Thomas@phantom
>> >    Well, not really, but wouldn’t that be a scary thought!

>> Well, yes really. They can record the average speed of traffic on
>> a particular road in addition to counting cars. This could lead to
>> the changing of a speed limit.
>Then that *is* a scary thought.  Why don’t they have cops hidden just
>beyond them to nail speeders?  (That’s the scary thought I was referring
>to.)

The things are useless for determining speed on moderately busy roads
unless they apply to only one lane.  I’ve never seen them set up that
way.

I imagine what they’re trying to do is determine car count and "free
speed" — the speed at which people travel when there’s not much
traffic.  They’d be good for that but there’d be a lot of spurious
data to throw out when cars are travelling next to each other.

A relative of mine invented the "ding ding thing."  I still have
prototypes laying around somewhere.  An amusing device.

jim frost
j…@centerline.com

>>>    Most are used to cound the number of cars that go through there, but
>>>some are used to measure speed by measuring the time it takes for you to
>>>get from the first one to the second one.

They are mainly used by local traffic engineers, but also by state
engineers, to monitor traffic.  You should be able to go down to your
city hall and see all sorts of maps showing traffic flow on major
arteries with big wide black arrows.  Here that information is used
to plan what roads might need to be widened and if traffic signals are
needed.  It also sets a service level that (by state law) determines
if additional development can occur feeding that road.  

Here I have also seen a person sitting at an intersection using a
device to log every vehicle — if it turned, what lane it was in,
etc etc — as part of some traffic monitoring / tax spending plan
that must be related to how the traffic signals are set.

In article <2e2o7k$…@bigboote.WPI.EDU>
darks…@bigwpi.WPI.EDU (David R Dorf) writes:

>Could also lead to a state losing highway funding, and/or subsequently
>increasing traffic patrols in the area, if the average-speed-measuring
>tubes were installed as a federal checkpoint..

The federal checkpoints are, as far as I know, at fixed locations on
interstate highways.  The ones I have seen are all loops in the pavement,
usually under bridges with the meter box off to the side on a pole.

The federal rules forbid any special traffic patrols and, in particular,
any radar monitoring, in the vicinity of these locations so that states
cannot bias the measurement by putting a radar gun near these very
few locations.  Of course, they are already biased if one location is
on a freeway with a lot of stop-and-go driving.

–
J. A. Carr       <j…@scri.fsu.edu>           |  "The New Frontier of which I  
Florida State University  B-186               |  speak is not a set of promises
Supercomputer Computations Research Institute |  – it is a set of challenges."
Tallahassee, FL  32306-4052                   |   John F. Kennedy (15 July 60)

The setup is like so:

—-
 I |————————– (Tube #2 for outside lane)
 S |———–                (Tube #2 for insude lane)
 L |
 A |
 N |————————- (Tube #1 for outside lane)
 D |———–               (Tube #1 for inside lane)
—-

–
  |o| Marshal Perlman                       Internet: perl…@cs.fit.edu |o|
  |o| Academic and Research Computing Services (ARCS)        IRC: Squawk |o|
  |o| Florida Institute of Technology                    FAA: PP-ASEL-IA |o|
  |o| Pager: 407/455-4809          Member: AOPA/AAAE/Goodyear Blimp Club |o|

My father used to tell about getting detected in that fashion
while, um, testing the capabilities of the V-nn Cadillac he had
before the war.  (Here nn == 10,12 and I’m sure the top end was
well beyond the capabilities of brakes and handling by today’s
standards.)  The ding-dingers were near the bottom of a long
downgrade, and the deed had been done by the time he realized
they were there.

So he floored it.

He actually didn’t get a ticket — I guess that some combination
of sheer speed and police drowsiness prevented a positive ID —
but while he took a pit stop in the next town, the nice officer
came along, surmised who it must’ve been, and engaged him in a
one-sided conversation about safety.

Happy motoring,
–Joe
"Just another personal opinion from the People’s Republic of Berkeley"
Disclaimer:  Even if my employer had a position on the subject,
 I probably wouldn’t be the one stating it on their behalf.

>In <Eh0Hjky00iV407e…@andrew.cmu.edu> ds…@andrew.cmu.edu (Derek B Shaffer) writes:

>>    Most are used to cound the number of cars that go through there, but
>>some are used to measure speed by measuring the time it takes for you to
>>get from the first one to the second one.
>>    Well, not really, but wouldn’t that be a scary thought!

>Well, yes really. They can record the average speed of traffic on
>a particular road in addition to counting cars. This could lead to
>the changing of a speed limit.  

Could also lead to a state losing highway funding, and/or subsequently
increasing traffic patrols in the area, if the average-speed-measuring
tubes were installed as a federal checkpoint..

DrD

>Then that *is* a scary thought.  Why don’t they have cops hidden just
>beyond them to nail speeders?  (That’s the scary thought I was referring
>to.)

They have used those here for detecting and ticketing speeders.  The
enforcement systems are made more discreet than the simple traffic-
counting or average-speed-calculating systems by using smaller tubing.
I haven’t seen any for a while so they may have fallen out of favour,
for whatever reasons.  Only scary if you don’t spot them in time.

Oh, another reason you may see two tubes on a traffic counting system
is that sometimes one will extend across both lanes of a road while the
other will cover only one.  Then the traffic in both lanes can be
counted independently without having to install two seperate counter
boxes.
—
Hugh Grierson                     Fujitsu New Zealand – Local Government Group
h…@fujitsu.co.nz [if that fails, try H.M.Grierson.nez1...@oasis.icl.co.uk]
Posting from the heart of summer.

>HELP! What are these things! They are making me crazy!

        I think they might be setup to trigger "punishment" lights.  Lights
that are set to turn red when people are exceeding the speed limit.  Often
you will see a sign that says this.  But they are very inaccurate.  By going
fast enough you can get through the light before it turns yellow.  So
I either speed a lot when I am in these areas, or I don’t speed.

:       I think they might be setup to trigger "punishment" lights.  Lights
: that are set to turn red when people are exceeding the speed limit.  Often
: you will see a sign that says this.  But they are very inaccurate.  By going
: fast enough you can get through the light before it turns yellow.  So
: I either speed a lot when I am in these areas, or I don’t speed.

HOW FAST? 100MPH? FASTER? 200MPH?

Break out your Vector!
—
  |o| Marshal Perlman                       Internet: perl…@cs.fit.edu |o|
  |o| Academic and Research Computing Services (ARCS)        IRC: Squawk |o|
  |o| Florida Institute of Technology                    FAA: PP-ASEL-IA |o|
  |o| Pager: 407/455-4809          Member: AOPA/AAAE/Goodyear Blimp Club |o|

>Excerpts from netnews.rec.autos.driving: 4-Dec-93 Re: "DING DING" THINGS
>IN ROAD by Graham E. Thomas@phantom
>> >    Well, not really, but wouldn’t that be a scary thought!

>> Well, yes really. They can record the average speed of traffic on
>> a particular road in addition to counting cars. This could lead to
>> the changing of a speed limit.
>Then that *is* a scary thought.  Why don’t they have cops hidden just
>beyond them to nail speeders?  (That’s the scary thought I was referring
>to.)

Because using them would be a violation of civil rights in most states.
The only reason a cop can use a radar gun is because he can determine
"probable cause" that you are speeding before hand.  A machine
indescriminately scanning every car passing by can not determine probable
cause.  This is the main defence against photo radar.

Anyone that has more information on this, like baring in different states
might wish to add to this.

  — Greg

–
————————————————————————
 "Autocrossers go in deeper and come out harder" 1991 Spirit R/T-G Stock
 B.S. Computer Sci., Minor Experimental Psychology – you figure it out
 "A day is how you play within it"  10/30/93