speeding offences

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Originally Posted by BobL

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Originally Posted by ian

If I can find it, I'll post the plot we did a few years ago of the speed / volume data from a 80km/h road

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Good

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Hi Bob

Here it is

Data is from Lane 1 of a two lane access controlled road in Sydney. I better not say which one.
Each data point represents the total number of vehicles using the Lane in an hour, plotted against the average speed of those vehicles. Data was collected over 4 "normal" weeks -- i.e. no public holidays, no school holidays in the period.
The traffic stream contains a significant number of very heavy vehicles which is reflected in the relatively low maximum volume.

You can readily see the interrelation of speed, volume and transit time and how the real world data matches the "model".

[QUOTE=ian;1852736]You can readily see the interrelation of speed, volume and transit time and how the real world data matches the "model"./QUOTE]

Hi Ian,

Just trying to make sure I understand your graph. The dots represent a plot of volume per hour and average speed? Does the dot, for example aligned at approximately 65 Km/hr on the vertical axis and aligned with about 700 vehicles on the horizontal axis represent a period of an hour's duration when 700 vehicles passed along the road at an average speed of 65 km/hr? Or is it longer or shorter time periods that are adjusted to vehicles per hour for consistency of data plotting? Or is it something completely different?

Doug

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Originally Posted by ian

Hi Bob

Here it is

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Great - thanks for that.
Good to see a real local example.
The ones I have seen have all been US or European but they are pretty similar.

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Originally Posted by doug3030

EDIT: I forgot to mention that when I was booked fo r101 in a 100 zone my "LEGAL: speedo for a pre-2006 vehicle would have been reading 97 - 98 km/hr.

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ADR's to my knowledge have always specified a speedometer that reads over?? Any links to where it was otherwise??

To save any confusion the ADR's specify that the speedo must be reading more than the actual road speed within a set tolerance.

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Originally Posted by BobL

Great - thanks for that.
Good to see a real local example.
The ones I have seen have all been US or European but they are pretty similar.

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thanks Bob

the important thing about that chart is that it the data represents real vehicles -- more normally the chart is expressed as passenger car units (PCUs)
PCU data is adjusted up by adding notional cars to the total vehicles by converting trucks to an "equivalent number" of cars.
The factors involved are too arcane for this discussion.

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Originally Posted by doug3030

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Originally Posted by ian

You can readily see the interrelation of speed, volume and transit time and how the real world data matches the "model".

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Hi Ian,

Just trying to make sure I understand your graph. The dots represent a plot of volume per hour and average speed? Does the dot, for example aligned at approximately 65 Km/hr on the vertical axis and aligned with about 700 vehicles on the horizontal axis represent a period of an hour's duration when 700 vehicles passed along the road at an average speed of 65 km/hr? Or is it longer or shorter time periods that are adjusted to vehicles per hour for consistency of data plotting? Or is it something completely different?

Doug

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Hi Doug

each data point represents the number of vehicles crossing the detector in 1 hour -- there are 24 records for each day each of 1 hour duration, the first starting at 1 second after mid-night and running through to 1:00AM
vehicles is the total number of VEHICLES crossing the detector in that hour.
average speed is the average speed of all vehicles crossing the detector within that hour.
Now a count of 700 vehicles in an hour could represent 500 cars and 200 trucks. Depending on a bunch of arcane factors, one big truck might be equivalent to 5 cars, so the 700 VEHICLES might be equivalent to 1500 Passenger Car Units (PCUs).
For the work we were doing at the time, grossing trucks up to PCUs wasn't necessary.

Is this permitted - confusing arguments with facts??

As we all know, gut feelings and personal hobbyhorses are much more reliable.