What are your thoughts on "no tolerance" on speed

[BlakJak]

at least i'm not alone in my thoughts on this.

The driver doing 107km/h is not going to kill you.

The driver doing 127 might.

The driver doing 107 and being inattentive might.

The driver doing 107 and not driving to conditions might.

Speed is easy to pick on; it's an objective measure. Sadly it's another screwup of the correleation-vs-causation type. And yes, I believe there's also an element of revenue gathering.

I'm a big fan of 'break the law, pay your dues' but I also admit to using the 10km/h tolerance liberally from time to time. But always to the conditions, and never when i'm distracted. Almost without exception, most of my frustration comes from drivers driving too slowly (or erraticallly), or making screwed up decisions - failing to think ahead. Like picking the wrong lane, or doing u-turns in silly places. Driver education would produce more tangible benefits for the motorists at large, and act less like a revenue magnet. It'd be a better PR move also. I feel a rant coming on...

[2jayzgte]

I get a sore ankle in my car if I don't at least put my foot anywhere near 1/2 throttle it iI leave it at say 100-110 kph for any length of time my foot goes to sleep so I feel I must give it a squiurt just to keep alert.I drove from Gisborne to WGTN over the weekend and kept at the above speeds with a bit of a squirt through State highway 50 and between Napier and Gisborne.

I find if I stay at the perscribed 100-105 without the odd squirt here and there I get very lethargic behind the wheel which in itself could be just as dangerous as speeding.

[Mr Revhead]

Warwick - my comment was about about speed displays in Victoria not in NZ

Ken

Oh yeeeeeaahhhh

[Leon]

My Pulsar reads 10% over actual road speed according to the GPS, so if you're sitting on 110 on the speedo that's bang on 100k. Not sure why, as the tyre and wheel size is all standard.

The g/f's Starlet Glanza is bang on accurate to within about 1kph.

I'm not too worried about a 5kph threshold for ticketing. Unless I'm seriously not paying attention to the world around me, I *know* when I'm 5kph over the speed limit in either of the two cars I commonly drive.

If I was in a big cruisy comfy quiet car, then I might have trouble sticking that closely to the speed limit.

[sergei]

I must admit, I am 100% aware of speed what I am doing and I was always doing 108 in 100. I am using this tolerance for passing lanes to my advantage. I am sure that my speedo is accurate because I measured with GPS/calculators/Your speed is signs and it is accurate within 1kph. The tyres are 5% larger than stock.

I find the problem is general populace will slow down greatly and will make travel even more painful. 70k in 100k zone is already very common.

[pjay]

I am sure that my speedo is accurate because I measured with GPS/calculators/Your speed is signs and it is accurate within 1kph

[Mr Revhead]

Who here knows exactly how accurate their GPS is?

[CXGPWR]

GPS are slow and will give you an estimated speed by calculating between two points. unless you spend thousands on a fantasticly amazing gps they will allways read slow.

[Mr Revhead]

So, your average speed between two points. I would assume those two points would depend on how many sattellites you're picking up at that time?
Not your realtime speed.....

[Malcolm]

GPS are slow and will give you an estimated speed by calculating between two points. unless you spend thousands on a fantasticly amazing gps they will allways read slow.

WTF are you talking about? Yes it works it out by calculating the time between two points, but that doesn't in any way mean it will always read slow.

As I mentioned earlier, I've done considerable work with verifying the accuracy of various speed measurement devices - the GPS we use is slightly more advanced than you average GPS navigator in that it updates at 5Hz rather than 1Hz that most operate at, and that would be accurate within 0.5% of true speed, provided you have a good GPS lock. I can't imagine your average consumer GPS would be worse than 1 or 2% error

[fivebob]

GPS are slow and will give you an estimated speed by calculating between two points. unless you spend thousands on a fantasticly amazing gps they will allways read slow.

How so???

The only way a GPS will read slow, regardless of how fantastically amazing it is, is if you are not travelling in a straight line. Otherwise the will read accurately, the longer the straight the more accurate they will read, and the faster the refresh rate the faster they will reach an accurate speed reading when transitioning from cornering to straight line speed.

[Mr Revhead]

So they "check in" with the satellitte as fast as once per second?
Is there a threshold of how many signals they need to be accurate?

[Malcolm]

So, your average speed between two points. I would assume those two points would depend on how many sattellites you're picking up at that time?
Not your realtime speed.....

All a GPS unit does is constantly calculates position, based on the time taken for a signal to arrive from a number of satellites. The more satellites you're picking up, the more accurately it knows your position. To calculate speed, it simply looks at how much your position has changed since the last calculation (and the time between the two). It will in fact give you less error (as a percentage) the faster you're going.

Typical accuracy for a GPS unit should be within 5m with a good signal. If you're driving slowly, you cover say 5m in the time between two calculations and each calculation is off at the worst limits of accuracy it could think you've done 15m and therefore give you a 200% error in speed. If you're going so fast you've done 500m between readings (unlikely) then 10m difference in that distance will only give you a 2% error.

[Mr Revhead]

cool

found this:
http://gpsinformation.net/main/gpsspeed.htm to explain it as well.

[Malcolm]

http://en.wikipedia.org/wiki/Gps#Positi ... troduction

3 signals is the minimum to guess your position on the surface of the earth. From there accuracy improves with every extra satellite. From what I've seen, 6 to 9 satellites is pretty common and there don't appear to be any obvious changes in accuracy between those (i.e. you don't suddenly see logged positions getting more or less scatter from where they should be)

[Malcolm]

[Adamal]

Bollocks to say that the no tollerance is the reason for reduced road toll.

If you tried to present it as a scientific experiment, it would be thrown out the window, as theres no control on other contributing factors.

[Mr Revhead]

Strangely mesmerising.....

[fivebob]

Typical accuracy for a GPS unit should be within 5m with a good signal. If you're driving slowly, you cover say 5m in the time between two calculations and each calculation is off at the worst limits of accuracy it could think you've done 15m and therefore give you a 200% error in speed. If you're going so fast you've done 500m between readings (unlikely) then 10m difference in that distance will only give you a 2% error.

That would be true if the error varied by 5m between readings. However unless the refresh rate is exceeding low (e.g. every minute) then the error should be consistent between readings. In the past when the military had "selective availabilty" switched on and the fix included a random error so that it was not consistent between readings. Selective availability hasn't been used since 2000 so the errors don't vary much between readings.

[sergei]

I am sure that my speedo is accurate because I measured with GPS/calculators/Your speed is signs and it is accurate within 1kph

What is with ?

Read comments above this one, to see that you can use GPS to relatively accurate measure speed, as long as you doing it right.

Also you can calculate how how much you travel per 1 revolution of a wheel by measuring circumference of the tyre (very easy to determine). Apply that to turn counter (speed sensor output) and you have a fairly accurate measuring device.

Combined with GPS and govt posted radars ("your speed is" signs) you can extrapolate how accurate the speedo is.