Author Topic: Have they got the speed wrong?  (Read 1640 times)

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Have they got the speed wrong?
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Hi everyone,

Shame about the old forum, but nvm.....

The TLDR is I was travelling South on M% - Tewkesbury, in managed section which was mainly 50mph, apart from one 40mph section which I recall. I'm adamant I adjusted my speed as I travel a lot as a contractor and 'always' use my limiter.

The only guide in the images are the lane markings (I have no idea what the yellow tram lines are trying to indicate?), so the pertinent question is what are the spacings of them? I've tried to look at the government website(s), but best I could ascertain is somewhere between 6-8m?

A transit custom SWB is 2933mm axle-axle, which appears to show my vehicle travelling around 2 x wheelbase in 0.35s, which is around 18m in 1s or 40mph.

To be travelling at 51mph as alleged, I would needed to have travelled 22.8m or ~8m in 0.35s......I think!  :-\

Is my maths correct, or am I way off with the distance?



First image, which I believe 'proves' nothing as I'm beyond the gantry: https://imgur.com/a/xmdKjqa

Second & third, taken 0.35s apart: https://imgur.com/a/ZJEroR8

I hope the images work, and thanks for any time spent everyone.

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Re: Have they got the speed wrong?
« Reply #1 on: »
First image, which I believe 'proves' nothing as I'm beyond the gantry: https://imgur.com/a/xmdKjqa
It's the auxiliary shot of the prevailing limit (40mph).  It seems you did miss this limit and didn't slow - It had changed well over 2 minutes earlier.

I have no idea what the yellow tram lines are trying to indicate?
They show the offending vehicle intersecting with the green circle.  HADECS3 RADAR system - all seems correct.

Second & third, taken 0.35s apart: https://imgur.com/a/ZJEroR8
My calculation is thus:

Distance travelled: Around 8m (Gap between lines is 7m, lines are 2m, so 7+1 - looking at shadow cast at rear onto lines)
So: 8/0.35 = ~23m/s = 51mph

To be travelling at 51mph as alleged, I would needed to have travelled 22.8m or ~8m in 0.35s......I think!  :-\
Correct - I'm not sure you can use the wheelbase effectively.  (Use a static point as I note above)
« Last Edit: August 30, 2025, 01:44:23 pm by JustLoveCars »
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Re: Have they got the speed wrong?
« Reply #2 on: »
Thanks for the reply - site wouldn't let me login for several hours.

Seems I had the maths correct, just the measurements wrong!

Oh well, I'll have to see what they say.....

Thanks again

Re: Have they got the speed wrong?
« Reply #3 on: »
Oh well, I'll have to see what they say.....
What have you done...?