Speed Cameras

It has been very interesting to read all the Government and Police reports
and replies on whether the speed cameras are accurate or not, acutally they
are saying that the speed cameras are very accurate, but they will be going
over them to check.
Then , out of the blue, they decide that some of them are giving wrong
readouts, so refunds will be forthcoing, but

What about all the other speed cameras , fixed or mobile ,
How accurate are they , how do they test them ,
How the hell can they be tested by an independant tester when the Police
will not allow them to be tested by anyone but their own ,
They reply that the cameras are checked by other speed cameras, but what if
the checking camera is out a bit,
Have you ever checked your speed by those overhead devices on the Hume
Highway ,
How accurate do you think they are ?
Go past them one day and your speed reading will be 95 kph ,
the next day your speed reading will be 105 kph., the next day it will be
different again,
this is probably why they tell you that they are not an accurate account of
your actual speed .
They are speed reading devices, the same as a speed reading camera .


A car which has lower pressure tyres, will read a different speed than one
with correct tyre pressure,
Not that much, you say, but just that little bit to make a difference .
I have played around with electronics for 30 years and I know that if a
component in the start of a circuit is faulty, e.g. a resistor or capicitor
which is supposed to be of a certain value goes a little high, then the rest
of the circuit is all out of whack,

Who is to say that all speed cameras are not faulty when they are not
allowed to be tested by a representative of the person who has been charged
with travelling above the speed limit.

My cruise control on the Fairlane was set at 98 kph , the speed went up to
101 after going over a hill, but the cop who was about a kilometer from me
coming toward me when he switched his flashers on , pulled me over stated
that my speed was 115, I looked at the device in the car and saw 115
flashing with 98 static, when I asked him why was it flashing, he said that
was standard .
What I didn't know was whether that speed reading was actually for me or for
the speed of another booking , or even his mates car, a white Commodore who
seemed to be travelling with him on the same stretch of road, because when
the greenie passed the whitie, the whitie flashed his lights as well, so it
was obvious they knew each other .


The loss of 3 points hit harder than $200.

 

But if the tyre pressure is too low, the indicated speed will be lower, not
higher than a car with correct pressure... and to over inflate a standard tyre
to read 5% higher than normal you'd have to increase the radius by 1.5cm...
that's gonna take more than a few psi.

Nev..

 

You missed the point, which was
If something at the start of the system was out,
then the final reading would also be out a greater degree

 

Speed cameras are supposed to improve safety on the roads, yet what they
manage to do is to force drivers to take their eyes off the road and focus
them on the speedo. Esp if you have an old holden or ford where the analogue
speedo goes up in increments of 20kms ..makes it bloody hard to judge the
diff between 65 and 69 kmph ..(the diff between a fine or no fine)
....digital speedos r much better for this

Fair enough if some idiot is doing 30-40kms over the limit then they
deservce to be fined but doing 5-8km over is abit ridiculous..at least in
the old days you had a chance to make up some bullshit excuse to the copper
...whether or not the excuse worked was another story

I'm waiting for the day when some law abiding citizen is busy checking his
speedo to find that hes doing spot on 50 kmph ..and thinking to themselves
what a safe sensible driver i am when wham they run over a kid who has
stepped out onto the road..Of course the driver didnt see them coz he/she
was too busy checking their speed.

Why cant the govt just get it through their heads that the roads r dangerous
and yes people die on them ..whatever you do or fines you impose people will
break the law..(check stats on the death penalty for this, it didnt slow
down murders at all) woopdee doo people die on the roads, people die from
drug over dosses, people drown, millions of people starve, get on with it
get a life ..fix the roads if you want ...or maybe fine slow drivers. i cant
begin to tell how many times i've seen people nearly have an accident becoz
they have been frustrated from a driver doing 20-30 kms under the limit and
in frustration try something dangerous to get past them. I wish they would
stop punishing the general popln for the actions of a few idiots.


rant rant rant
rave rave ...blah blah

 

I can remember 20 years back of going on military leave twice a year &
heading interstate at 160+ plus on my 1000 what ever i was riding at the
time. Its all over mate...they are just memorys now. But hell they are good
memories. **** the fun police.

 

Yeah Nev, you know those decals on the Blackbird tank?

They're _butterfly wings_...

big

 

Curiously the effect is very minor because the circumference of a steel
belted radial is pretty constant even at different tyre pressures.

Compared to the +/-10% accuracy requirement it's trivial.

 

No.
This is a simple linear system.
If the circumference of the tyres is increased by 2%, the actual speed
at the same indicated speed increases by 2%.

Not by 4%. Not by 12%. Just 2%.

 

Playing around with electronics?

Start developing a transmitter to burn the bastards out then.

 

It will need to be infrared ...maybe 5 watts. Im experimenting ATM

 

I think the response he was looking for goes something long the lines of

"It's the constitution, it's Mabo … it's the vibe!"

Nev..

 

I think the response he was looking for goes something long the lines of

"It's the constitution, it's Mabo . it's the vibe!"

Nev..
The answer Nev is, just like a snowball efect
Graham W obviously doesnt know that much about electronics and the effect of
a faulty component at the start of the circuit
as compared to a faulty component at the end of it.

2% less fuel at the motor is far worse than 2% less air in the tyres.

 

Would do if I could get hold of a speed detection device such as the ones
they use,
but as I said before, they won't let anyone have or test one.

 

Actually I have found them to be very consistent. 111 indicated on both of my
CBR1100s with Bridgestone tyres at the recommended pressure measured 103kph on
the speed checkers on Hume Hwy Kalkallo, Hume Hwy Wodonga, Princes Fwy Geelong
and the Western Fwy out near Melton.

Nev..

 

2% less fuel at the motor is probably not going to cause the detected speed to
read higher either.

Nev..

 

The roadworks at the Goulburn end of the Federal Highway had one of
those portable ones on a trailer. One day my accurate-reading speedo
showing 110km/h was measured at 104km/h. The next day my same speed
was measured at 75km/h!

 

The same technology is used for prosecution.

 

I've had funny results from those. Generally they seem accurate (at least
they match my speedo within 1 or 2 km/h).
However, at times I've been going faster than the car next to me, yet that
car reads a higher speed than me.
Go figure.

 

And we can only presume now that you're going to provide a list of cases where
the prosecution gained a successful conviction based on the use of evidence
provided by privately owned trailer mounted speed measuring technology...

Nev..

 

Stop and think about what you're saying.

The whole point of a speedometer is that if you drive 2% faster it reads
2% higher. Not 4%. Not 12%. The relationship between the rate of
rotation of the wheels and the indicated speed must be linear or it's
not a speedometer.

Sure you can build an electronic circuit where the relationship between
the value of one component and some output value is a cube or 4th power,
but a speedometer is inherently going to be designed for a linear
relationship between input and output. Otherwise it wouldn't be a speedo.