..because everyone slows down for them but I’ve only met people who’ve been done by gatsos. Are they….EVEN ON???

http://www.dailyrecord.co.uk/news/scottish-news/average-speed-cameras-cost-drivers-6708388#PkXasjGk1rb5yQcL.97

400 odd people reportedly got done in four days when they had them on the M275 a couple of years ago. Despite leaving warning signs up for weeks before and a huge PR campaign by Hants police!

Colleague got done on the M62 when they had them near Leeds. Had to explain to him in very simple terms how distance equals speed over time. Muppet was just slowing down at the cameras!

MrsT got done in Southport, she did the “correction” course rather than taking points. On the course there was a guy from Wales who had been caught for the third time 🙄

I’m sure the ones currently installed on the Glasgow road works will be raking it in given some of the madness I witnessed recently.

The M6 Carlisle works made a nob or two;
http://www.dailymail.co.uk/news/article-1256738/Speed-camera-trap-M6-racing-record-3m-haul-fines.html

A bit of googling answers your question;
http://www.manchestereveningnews.co.uk/news/greater-manchester-news/m6-speed-camera-dishes-out-8811348

Don’t all speed cameras measure ‘average’ ? It’s just the distance / time over which that average is measured which varies.

True i suppose, Marcus!

Yes l loads of overripe do show down for the cameras. I always wonder of they think that average is the average of the speed they go through each camera at..?

Especially annoying on the a9 where loads of cars slow down to 50…

Muppet was just slowing down at the cameras!

Despite having these on a 5 mile stretch of my local DCW for about 10 years, it’s amazing how many people you see still doing this!

Disappointed, expected thread to be about members basking in the glory of being caught on camera exceeding permitted road speeds on their bikes. 😉

Don’t all speed cameras measure ‘average’ ? It’s just the distance / time over which that average is measured which varies.

LOL. Impressive level of pedantry there. I think the policeman-holding-gun type is instantaneous speed though.

Load of mouth breathers from my home town crying about being caught in the new bit of managed motorway on the m1 despite the 10 foot by 15 warning signs . No one is going to be dumb enough to own up to being so incapable of controlling their car that they get caught by a set of average cameras even if you are not paying attention and speed through one you have ages to reduce your average speed to below the limit.

I was done twice on the stretch between Stocksbridge and J36 M1, twice in ten days, the NIPS were 3 weeks apart so didn’t hear about the 2nd until I returned home after a week overseas, so 6 points for 3 full years, when there is a good chance you could easily lose your job it tends to focus the mind a bit better, the fuel saving and therefore my mileage claims improved though.

THINK ON !!!!!!!!!!!! 😉

Don’t all speed cameras measure ‘average’ ? It’s just the distance / time over which that average is measured which varies.

It measures your speed at the point you pass the camera
Not sure why you want to claim one measure at one point is an average
Can you explain the pedantry to me please?

He means that a tradition speed camera takes two pictures. The speed is found by dividing the distance traveled by the car in the two photos by the time between the two photos. So he’s correct, this is also an average.

On a similar note, I’ve often wondered how you can be prosecuted for exceeding 50 miles per hour, when you haven’t travelled 50 miles or travelled for an hour ? Surely a speed limit of metres per second would be more appropriate

As is the hand held one I think – measures how far away you are, measures it again a set time later, works out the distance you’ve covered in that time. So applying he same logic that’s average speed too. Average speed over about 2-3 seconds I suppose (that’s how long they take the old ones took to get a reading.

On a similar note, I’ve often wondered how you can be prosecuted for exceeding 50 miles per hour, when you haven’t travelled 50 miles or travelled for an hour ? Surely a speed limit of metres per second would be more appropriate

Good morning Mr Taylforth.

Don’t some hand held ones work by doppler shift?

Possibly because it’s 22.352metres per second….

Is that radar? I think there are some radar ones still on the go but it’s mostly laser ones as they are, well, much better all round as I understand it.

Don’t some hand held ones work by doppler shift?

That’s basically how RADAR works, but it’s old tech as far as speed cameras go. I’d be surprised if it’s still in use (in the UK at any rate).

@rich mars
Ta

Do the M25 ones work?

When the overhead gantry speed signs show 60 for instance you still see folks rattling along at least 20-30-40 plus mph over that…

I do wonder if anyone knows how/why these things work.

When the M1 in Derbyshire had an average 50 limit for the roadwork between junction 28 and 31 they caught around 100 drivers a day over the two years or so it was in operation. According to our local paper one guy got done three times!

By my pig-physics reckoning, you can’t measure speed instantaneously since v = d/t. If t=0 then v can only be infinite (or 0 I guess).

I might be pedantic, but IANAPhysicist. 🙂

I was done twice on the stretch between Stocksbridge and J36 M1, twice in ten days, the NIPS were 3 weeks apart so didn’t hear about the 2nd until I returned home after a week overseas, so 6 points for 3 full years, when there is a good chance you could easily lose your job it tends to focus the mind a bit better, the fuel saving and therefore my mileage claims improved though.

THINK ON !!!!!!!!!!!!

Are you sure it was the average cameras?

They Park the scamera van on the bridge also with its side window pointing down the bypass

Basically you could have done 20 mph all the way along there but just as your overtaking at 67mph up the hill BANG they nail you between the avg cameras

crafty buggers

I see your ‘logic’ but you can have velocity at a particular point in time. If you don’t, then you also have no kinetic energy (since KE = 1/2 mv^2) and if you have no KE then where’s it gone / you’ll have to rewrite general relativity. And that’s too difficult for a Monday morning.

richmars – Member

Don’t some hand held ones work by Doppler shift?

Used to, but it is not an instantaneous speed measurement.
Speed = distance/time, you have to have both to work it out so all speed measurement is an average.

Aren’t velocity and speed different things ?

Aren’t velocity and speed different things ?

Velocity is a vector ie has direction whereas speed doesn’t.

http://www.bristolpost.co.uk/M4-M5-speed-cameras-temporary-speed-limit-signs/story-25866420-detail/story.html

the cameras on the M4 and M5 on the approaches to the Almondsbury Interchange are have been used more than 5,000 times to catch drivers exceeding the 70mph limit in the past seven months, leading to fines totalling more than £500,000 being issued.

I see your ‘logic’ but you can have velocity at a particular point in time. If you don’t, then you also have no kinetic energy (since KE = 1/2 mv^2) and if you have no KE then where’s it gone / you’ll have to rewrite general relativity

You can state a velocity at an instantaneous point in time, but the only way you’ll know what that velocity is, is by measuring over time, either side of that point.
The instantaneous point in time doesn’t exist, so KE and relativity laws are safe.

you’ll have to rewrite general relativity. And that’s too difficult for a Monday morning

Give me enough coffee and a place to stand and I will move the universe!

Velocity is a vector ie has direction whereas speed doesn’t.

You’ve seen my mum drive too?

I too had a colleague that was convinced average speed meant they took your ‘instantaneous’ speeds at all the cameras, added them up and divided by the number of cameras to give his average of all.

The fact he never got ticketed was mainly because other traffic moving at 50-odd slowed him down sufficiently that his constant speed up / slow down style never got his average sufficiently high (they must have quite a degree of leeway)

But unfortunately, he also saw the fact that he didn’t get ticketed as validation that his opinion was right 🙄

a similar note, I’ve often wondered how you can be prosecuted for exceeding 50 miles per hour, when you haven’t travelled 50 miles or travelled for an hour ? Surely a speed limit of metres per second would be more appropriate

I like your thinking!
Do you send a bill to your bank when you get money out from one of those ‘Free Cash Machines’ and the money gets taken from your account?

Do the M25 ones work?

When the overhead gantry speed signs show 60 for instance you still see folks rattling along at least 20-30-40 plus mph over that…

I do wonder if anyone knows how/why these things work.

Not every gantry has a camera, you can see which ones do from quite a long way back.

They’ve just replaced a couple of GATSOs on the A316 with average cameras over the whole bit (well from the end of the M3 up to Richmond). Fairly sure that will result in a bit in the local newspaper shortly…

For anyone that does the M4 managed section around Bristol occasionally, there are a couple (1 each direction) of speed cameras which are pinned to the LHS of the gantry support. I’m fairly sure these are also linked to the mandatory speed limits which are imposed during congestion, but also they’ll flash when no speed-limit is indicated on overheads. I may have seen some overhead ones flashing but I’ve seen those two pinging lots of people. Had a 4 week-ish period where I was doing that section from M5 to M32 every morning/evening and there was hardly a day I didn’t see both of them flashing drivers.

surely if you obey the speed limit these cameras are not an issue? 😕

ah, Mr Killington. We’ve been expecting you.

You have to be careful with the laser ones; especially if you have a blue car…

The laser also works essentially using the doppler effect – a laser is sent out at a know frequency and it bounces back off the bonnet of a moving vehicle. Because the “effective” frequency of the reflection received is higher by a known amount, the speed of the vehicle can be calculated.

Now, the trouble is; if you are driving a blue car, blue light is a higher frequency than red light and it has the effect of changing the reflected laser light that little bit more than a red car does and means you can be measured doing a higher speed than you actually are.

That’s why they have to have some leeway in the system.

They don’t tell you these things, do they??? 😉

Rachel