Average Speed Camera's and ACPO | Motoring discussion | Back Room Forum

What is life like with your car? Let us know and win £500 in John Lewis vouchers | No thanks

Fri 10 Dec 2021 19:24

Average Speed Camera's and ACPO - fredthefifth

Dunno if anyone else feels the same but its seems to me that more vehicles than ever are driving to the limit of the ACPO guidelines.

My reasoning - Despite having a GPS speed indicator in my car I will normally set my speed limiter or cruise to the specified limit for a bit of margin, however sometimes I will push the speed up so the GPS indicates the specifies speed. In a 50 limit in my car this is normally 53mph on the speedo, 50mph on the GPS. Even at that increased speed cars and lorries are passing at a good few mph faster than me. Given that in a 50 limit ACPO guidelines allow a true speed of 57mph, that would be around 60mph on most speedos, I reckon that is is the limit that is being pushed by more drivers than ever these days.

What's more some of them, particularly the lorries I'm affraid, drive very aggressively towards anyone not doing the same.

Reply | Report as offensive | Link

Fri 10 Dec 2021 19:30

Average Speed Camera's and ACPO - RT

Correction - ACPO guidelines "allow" limit + 10% + 1mph, so 56 in a 50 - at 57 that's the threshold for the start of proceedings.

HGVs generally rely on their limiter so it's foot to the floor in a 50.

Reply | Report as offensive | Link

Fri 10 Dec 2021 20:17

Average Speed Camera's and ACPO - fredthefifth

Sorry, my mistake, however 1mph doesn't change my basic point.

And if HGV's are relying on their limiter then my experience is that its set a fair bit higher than a real speed of of 50mph.

Reply | Report as offensive | Link

Fri 10 Dec 2021 20:37

Average Speed Camera's and ACPO - badbusdriver

Most modern trucks have a 90km/h (56mph) limiter. Older trucks and all buses will have a100km/h (62mph) limit.

From my own experience driving buses, there wasn't much variations in what the limiter would allow on buses which, at the time ('03-'09) were quite new. On older buses, most would go to an indicated 60-64mph but some might just breach 65mph and I remember at least one Volvo B10 coach on which the limiter didn't work...............

But given the time pressures most truck drivers are under, it is only to be expected that they are going as fast as they can get away with.

Reply | Report as offensive | Link

Sat 11 Dec 2021 09:29

Average Speed Camera's and ACPO - Andrew-T

Most modern trucks have a 90km/h (56mph) limiter. Older trucks and all buses will have a 100km/h (62mph) limit.

Yes, that'll be why we keep seeing rolling roadblocks on the M'way, where one truck can manage 0.2mph more than another but will never give up trying to pass the slower one, even when it's obvious that will take a couple of miles or more.

Reply | Report as offensive | Link

Fri 10 Dec 2021 22:32

Average Speed Camera's and ACPO - galileo

Correction - ACPO guidelines "allow" limit + 10% + 1mph, so 56 in a 50 - at 57 that's the threshold for the start of proceedings.

HGVs generally rely on their limiter so it's foot to the floor in a 50.

I think the guidelines are 10% + 2 mph, the 2 mph is "to allow for device tolerance"

Reply | Report as offensive | Link

Fri 10 Dec 2021 22:42

Average Speed Camera's and ACPO - bathtub tom

I think the guidelines are 10% + 2 mph, the 2 mph is "to allow for device tolerance"

I wouldn't rely on that. I know of one person who maintains they were done for doing 31 in a 30. Bournemouth area.

Reply | Report as offensive | Link

Sat 11 Dec 2021 11:14

Average Speed Camera's and ACPO - John F

I think the guidelines are 10% + 2 mph, the 2 mph is "to allow for device tolerance"

I wouldn't rely on that. I know of one person who maintains they were done for doing 31 in a 30. Bournemouth area.

Misperception and delusion are widespread human characteristics. I am quite content to trundle past speed cameras with the cruise control set to a few mph, i.e. up to 10%, above the posted limit, weather and traffic conditions permitting.

Reply | Report as offensive | Link

Sat 11 Dec 2021 00:06

Average Speed Camera's and ACPO - focussed

Correction - ACPO guidelines "allow" limit + 10% + 1mph, so 56 in a 50 - at 57 that's the threshold for the start of proceedings.

HGVs generally rely on their limiter so it's foot to the floor in a 50.

I think the guidelines are 10% + 2 mph, the 2 mph is "to allow for device tolerance"

Correct - it always was L+10% + 2

Reply | Report as offensive | Link

Sat 11 Dec 2021 06:47

Average Speed Camera's and ACPO - RT

Correction - ACPO guidelines "allow" limit + 10% + 1mph, so 56 in a 50 - at 57 that's the threshold for the start of proceedings.

HGVs generally rely on their limiter so it's foot to the floor in a 50.

I think the guidelines are 10% + 2 mph, the 2 mph is "to allow for device tolerance"

The 10% +2 mph is where proceedings start

Look at the table in this link, 57 mph in a 50 is a fixed penalty ACPO Guidelines (pepipoo.com)

Edited by RT on 11/12/2021 at 06:49

Reply | Report as offensive | Link

Sat 11 Dec 2021 17:36

Average Speed Camera's and ACPO - fredthefifth

Whether its 10% plus 1 or 2mph, I'm definitely getting the impression that drivers in general are taking advantage of the ACPO guidelines.

Are lorry speedo's more accurate than cars? It would explain why in 50mph zones with average speed camera's, lorry's are a couple of mph faster than cars and sometimes drive very aggressively to get them to move over.

Reply | Report as offensive | Link

Sat 11 Dec 2021 21:38

Average Speed Camera's and ACPO - galileo

Whether its 10% plus 1 or 2mph, I'm definitely getting the impression that drivers in general are taking advantage of the ACPO guidelines.

Are lorry speedo's more accurate than cars? It would explain why in 50mph zones with average speed camera's, lorry's are a couple of mph faster than cars and sometimes drive very aggressively to get them to move over.

LGV tachos are calibrated to be accurate (as are Traffic Police car speedometers)

Ordinary car speedometers over-read by at least 2 mph - mine reads 50 mph at a true 48 mph per Satnav on a straight, level road. It reads 70 at a true 68, some cars I have had were 3 mph optimistic.

This is why LGVs pass you (legally) in 50 or other limits if you rely on your speedo reading.

Long ago, it was suspected that some manufacturers deliberately arranged for speedos to be optimistic to flatter the performance of their cars, and the degree of over-reading was not always constant, being greater at higher speeds with traditional speedometers,

Edited by galileo on 11/12/2021 at 21:53

Reply | Report as offensive | Link

Sun 12 Dec 2021 05:45

Average Speed Camera's and ACPO - RT

Whether its 10% plus 1 or 2mph, I'm definitely getting the impression that drivers in general are taking advantage of the ACPO guidelines.

Are lorry speedo's more accurate than cars? It would explain why in 50mph zones with average speed camera's, lorry's are a couple of mph faster than cars and sometimes drive very aggressively to get them to move over.

LGV tachos are calibrated to be accurate (as are Traffic Police car speedometers)

Ordinary car speedometers over-read by at least 2 mph - mine reads 50 mph at a true 48 mph per Satnav on a straight, level road. It reads 70 at a true 68, some cars I have had were 3 mph optimistic.

This is why LGVs pass you (legally) in 50 or other limits if you rely on your speedo reading.

Long ago, it was suspected that some manufacturers deliberately arranged for speedos to be optimistic to flatter the performance of their cars, and the degree of over-reading was not always constant, being greater at higher speeds with traditional speedometers,

The reason is quite different - speedometers are required to be optimistic by law, they're not allowed to under-read - typically between +0% and +10%.

My speedometer is almost exactly correct - I've fitted slightly larger tyres when replacements were needed and a GPS readout confirms that actual speed and speedometer speed are the same - of course that's to the nearest 1 mph as they aren't calibrated any finer.

Reply | Report as offensive | Link

Sun 12 Dec 2021 09:47

Average Speed Camera's and ACPO - John F

My speedometer is almost exactly correct - I've fitted slightly larger tyres when replacements were needed .........

Same here. I fitted 255/45/19 instead of 255/40/19 to my Audi A8 because they were half the price.....for more actual tyre material! This resulted in a diameter increase, and thus speedo error, of 3.7%.

Reply | Report as offensive | Link

Sun 12 Dec 2021 22:22

Average Speed Camera's and ACPO - nick62

Having just elected to pay £90 to be patronised for three hours, I can confirm that 10% +2 mph will get you a ticket.

I've just been done for doing 68 in a variable 60 limit where the M6 and M6 toll merge near Corley, by a fixed camera.

Edited by nick62 on 12/12/2021 at 23:06

Reply | Report as offensive | Link

Mon 13 Dec 2021 13:10

Average Speed Camera's and ACPO - fredthefifth

I had always thought that the tacho's on lorries would be accurate and that explains why lorries can legally pass a car doing 50mph on their speedo. Thanks for confirming.

As I've said above, in 50mph average speed zones when driving at a gps speed of 50mph cars and lorries are flying past. Presumably pushng the 56mph ACPO guidelines. That was the basis of my OP.

A side point is that some lorry drivers will inevitably catch up cars in lane 2, and even lane 3 on occasions, and drive very aggressively to get them to move over.

Reply | Report as offensive | Link

Mon 13 Dec 2021 13:15

Average Speed Camera's and ACPO - _

I had always thought that the tacho's on lorries would be accurate and that explains why lorries can legally pass a car doing 50mph on their speedo. Thanks for confirming.

As I've said above, in 50mph average speed zones when driving at a gps speed of 50mph cars and lorries are flying past. Presumably pushng the 56mph ACPO guidelines. That was the basis of my OP.

A side point is that some lorry drivers will inevitably catch up cars in lane 2, and even lane 3 on occasions, and drive very aggressively to get them to move over.

That is where my rear facing camera helps, with the big sticker on the hatch saying you are being filmed !

Reply | Report as offensive | Link

Ask Honest John

Sell Your Car

Real MPG

Fuel Calculator