Blanket 20mph in Wales - stopping distances lie?
Discussion
This imposition is looming at a cost of £40m despite 90% opposition. Most of us would support a more limited implementation in proper residential areas, in High Streets and by schools of course. BBC today running a story with this graphic which I consider total misinformation.

I KNOW my 2,300kg Taycan stops in under its own 5m length - done it at Silverstone PEC course. Why do they say 14 metres then? Is there any accuracy there or is it all scare the public to get them to do what you want, as is increasingly the norm?
I KNOW my 2,300kg Taycan stops in under its own 5m length - done it at Silverstone PEC course. Why do they say 14 metres then? Is there any accuracy there or is it all scare the public to get them to do what you want, as is increasingly the norm?
I argued this on a speed awareness course (definitely the wrong thing to do).
But the zealot hosting the course was adamant that the the Highway Code was correct. Even though I quoted the stopping times for my AMG Mercedes that I was caught doing 46 in a 40.
His argument was if you were not breaking the speed limit you would be able to stop sooner.
Which I countered with even at 46mph my car stops quicker than the Highway Code says that a car doing 30 mph stops. And probably 20 mph!
To which his counter argument was "you still shouldn't have been speeding".
Top tip, never say a word on a speed awareness course. They then ask your opinion on everything.
Keep your mouth shut and you can get away with 3 hours of daydreaming instead.
But the zealot hosting the course was adamant that the the Highway Code was correct. Even though I quoted the stopping times for my AMG Mercedes that I was caught doing 46 in a 40.
His argument was if you were not breaking the speed limit you would be able to stop sooner.
Which I countered with even at 46mph my car stops quicker than the Highway Code says that a car doing 30 mph stops. And probably 20 mph!
To which his counter argument was "you still shouldn't have been speeding".
Top tip, never say a word on a speed awareness course. They then ask your opinion on everything.
Keep your mouth shut and you can get away with 3 hours of daydreaming instead.
Geoffcapes said:
Top tip, never say a word on a speed awareness course. They then ask your opinion on everything.
Keep your mouth shut and you can get away with 3 hours of daydreaming instead.
Thanks for this. If I ever have to go on one I will try not to cough false at every opportunity. Keep your mouth shut and you can get away with 3 hours of daydreaming instead.
As for 20s, yeah they're utterly ridiculous, especially when like around here, the wide laned, giant pavemented, straight, previously 40 zones are being changed.
It's just another way of getting people to hate driving.
Geoffcapes said:
I argued this on a speed awareness course (definitely the wrong thing to do).
But the zealot hosting the course was adamant that the the Highway Code was correct. Even though I quoted the stopping times for my AMG Mercedes that I was caught doing 46 in a 40.
His argument was if you were not breaking the speed limit you would be able to stop sooner.
Which I countered with even at 46mph my car stops quicker than the Highway Code says that a car doing 30 mph stops. And probably 20 mph!
To which his counter argument was "you still shouldn't have been speeding".
Top tip, never say a word on a speed awareness course. They then ask your opinion on everything.
Keep your mouth shut and you can get away with 3 hours of daydreaming instead.
I queried this on a speed awareness course. Politely.But the zealot hosting the course was adamant that the the Highway Code was correct. Even though I quoted the stopping times for my AMG Mercedes that I was caught doing 46 in a 40.
His argument was if you were not breaking the speed limit you would be able to stop sooner.
Which I countered with even at 46mph my car stops quicker than the Highway Code says that a car doing 30 mph stops. And probably 20 mph!
To which his counter argument was "you still shouldn't have been speeding".
Top tip, never say a word on a speed awareness course. They then ask your opinion on everything.
Keep your mouth shut and you can get away with 3 hours of daydreaming instead.
Apparently, Highway Code stopping distances are based on a 1950s Hillman Minx.
He argued that the difference in modern cars was not that great as the thinking distance is always the same. I observed that even a light car with four small drum brakes could never hope to emulate a servo-assisted, brake-assisted, four disc-braked car that (ignoring ABS) wasn't going to lurch and throw all its weight onto its cross-ply tyres.
Apparently, I didn't have to do the course and could leave and have the points.
We moved on...
As for 20 limits, they are ridiculous. Lower gear so more emissions, most drivers no longer paying attention and driving in their sleep, pedestrians with a new Highway Code imbued indestructibility, treating roads like pedestrianised areas, bicycles flying past your window, increased queues at junctions as drivers "not quite sure" if they can accelerate to 20 before your car arrives a week next Thursday...
As a fairly regular Bristol airport user, I am always gobsmacked just how ineffective the "average 50mph" limits are. It certainly doesn't seem to reduce the high frequency of accidents that often totally fex up your journey. Last time, an accident closed the bridge and it took well over an hour to crawl up the M48 at 5mph and resulted in a speed dash to catch the plane by the smallest of margins.
Edited by LuS1fer on Friday 18th August 10:32
The tyres are the huge difference. I think people under-estimate quite how much tyres have improved in even the last ten years let alone the last 70!
Tyre reviewers often run objective braking tests on some sort of bog-standard family hatchback and the results of the best mainstream summer tyres in the dry typically come out somewhere around half the highway code figures. Even the worst budget tyres in the wet generally beat the highway code's figures.
Tyre reviewers often run objective braking tests on some sort of bog-standard family hatchback and the results of the best mainstream summer tyres in the dry typically come out somewhere around half the highway code figures. Even the worst budget tyres in the wet generally beat the highway code's figures.
Edited by kambites on Friday 18th August 10:41
LuS1fer said:
Geoffcapes said:
I argued this on a speed awareness course (definitely the wrong thing to do).
But the zealot hosting the course was adamant that the the Highway Code was correct. Even though I quoted the stopping times for my AMG Mercedes that I was caught doing 46 in a 40.
His argument was if you were not breaking the speed limit you would be able to stop sooner.
Which I countered with even at 46mph my car stops quicker than the Highway Code says that a car doing 30 mph stops. And probably 20 mph!
To which his counter argument was "you still shouldn't have been speeding".
Top tip, never say a word on a speed awareness course. They then ask your opinion on everything.
Keep your mouth shut and you can get away with 3 hours of daydreaming instead.
I queried this on a speed awareness course. Politely.But the zealot hosting the course was adamant that the the Highway Code was correct. Even though I quoted the stopping times for my AMG Mercedes that I was caught doing 46 in a 40.
His argument was if you were not breaking the speed limit you would be able to stop sooner.
Which I countered with even at 46mph my car stops quicker than the Highway Code says that a car doing 30 mph stops. And probably 20 mph!
To which his counter argument was "you still shouldn't have been speeding".
Top tip, never say a word on a speed awareness course. They then ask your opinion on everything.
Keep your mouth shut and you can get away with 3 hours of daydreaming instead.
Apparently, Highway Code stopping distances are based on a 1950s Hillman Minx.
He argued that the difference in modern cars was not that great as the thinking distance is always the same. I observed that even a light car with four small drum brakes could never hope to emulate a servo-assisted, brake-assisted, four disc-braked car that (ignoring ABS) wasn't going to lurch and throw all its weight onto its cross-ply tyres.
Apparently, I didn't have to do the course and could leave and have the points.
We moved on...
As for 20 limits, they are ridiculous. Lower gear so more emissions, most drivers no longer paying attention and driving in their sleep, pedestrians with a new Highway Code imbued indestructibility, treating roads like pedestrianised areas, bicycles flying past your window, increased queues at junctions as drivers "not quite sure" if they can accelerate to 20 before your car arrives a week next Thursday...
As a fairly regular Bristol airport user, I am always gobsmacked just how ineffective the "average 50mph" limits are. It certainly doesn't seem to reduce the high frequency of accidents that often totally fex up your journey. Last time, an accident closed the bridge and it took well over an hour to crawl up the M48 at 5mph and resulted in a speed dash to catch the plane by the smallest of margins.
Edited by LuS1fer on Friday 18th August 10:32
Why anyone would be so naive as to query them is beyond me. A persons opinion on the matter is utterly irrelevant and trying to discuss it during a speed awareness course which the required attendance in itself indicates poor driving is indicating even more stupidity.
https://assets.publishing.service.gov.uk/media/559...
The exact distance is largely irrelevant, and will be different for every single vehicle and set of road conditions. The ratiometric difference in stopping distance between 20mph and 30mph will still hold roughly true whatever the actual distances are, as does the difference in outcomes from being hit by a car at different speeds.
grudas said:
ucb said:
Because the highway code stopping distances have not been updated in a lifetime?
yup, the data is from what, the 70s? they really need to update this.Ken Figenus said:
This imposition is looming at a cost of £40m despite 90% opposition. Most of us would support a more limited implementation in proper residential areas, in High Streets and by schools of course.
Local councils have reviewed the regulations, as they are obliged/allowed and not all 30mph limits are changing to 20mph, not by a long chalk.Nomme de Plum said:
LuS1fer said:
Geoffcapes said:
I argued this on a speed awareness course (definitely the wrong thing to do).
But the zealot hosting the course was adamant that the the Highway Code was correct. Even though I quoted the stopping times for my AMG Mercedes that I was caught doing 46 in a 40.
His argument was if you were not breaking the speed limit you would be able to stop sooner.
Which I countered with even at 46mph my car stops quicker than the Highway Code says that a car doing 30 mph stops. And probably 20 mph!
To which his counter argument was "you still shouldn't have been speeding".
Top tip, never say a word on a speed awareness course. They then ask your opinion on everything.
Keep your mouth shut and you can get away with 3 hours of daydreaming instead.
I queried this on a speed awareness course. Politely.But the zealot hosting the course was adamant that the the Highway Code was correct. Even though I quoted the stopping times for my AMG Mercedes that I was caught doing 46 in a 40.
His argument was if you were not breaking the speed limit you would be able to stop sooner.
Which I countered with even at 46mph my car stops quicker than the Highway Code says that a car doing 30 mph stops. And probably 20 mph!
To which his counter argument was "you still shouldn't have been speeding".
Top tip, never say a word on a speed awareness course. They then ask your opinion on everything.
Keep your mouth shut and you can get away with 3 hours of daydreaming instead.
Apparently, Highway Code stopping distances are based on a 1950s Hillman Minx.
He argued that the difference in modern cars was not that great as the thinking distance is always the same. I observed that even a light car with four small drum brakes could never hope to emulate a servo-assisted, brake-assisted, four disc-braked car that (ignoring ABS) wasn't going to lurch and throw all its weight onto its cross-ply tyres.
Apparently, I didn't have to do the course and could leave and have the points.
We moved on...
As for 20 limits, they are ridiculous. Lower gear so more emissions, most drivers no longer paying attention and driving in their sleep, pedestrians with a new Highway Code imbued indestructibility, treating roads like pedestrianised areas, bicycles flying past your window, increased queues at junctions as drivers "not quite sure" if they can accelerate to 20 before your car arrives a week next Thursday...
As a fairly regular Bristol airport user, I am always gobsmacked just how ineffective the "average 50mph" limits are. It certainly doesn't seem to reduce the high frequency of accidents that often totally fex up your journey. Last time, an accident closed the bridge and it took well over an hour to crawl up the M48 at 5mph and resulted in a speed dash to catch the plane by the smallest of margins.
Edited by LuS1fer on Friday 18th August 10:32
Why anyone would be so naive as to query them is beyond me. A persons opinion on the matter is utterly irrelevant and trying to discuss it during a speed awareness course which the required attendance in itself indicates poor driving is indicating even more stupidity.
https://assets.publishing.service.gov.uk/media/559...
Pica-Pica said:
Ken Figenus said:
This imposition is looming at a cost of £40m despite 90% opposition. Most of us would support a more limited implementation in proper residential areas, in High Streets and by schools of course.
Local councils have reviewed the regulations, as they are obliged/allowed and not all 30mph limits are changing to 20mph, not by a long chalk.As for the braking distance argument: you can easily counter the better brakes by the more distractions there are and that most drivers aren't paying any attention to driving anyway.
TurboHatchback said:
The exact distance is largely irrelevant, and will be different for every single vehicle and set of road conditions. The ratiometric difference in stopping distance between 20mph and 30mph will still hold roughly true whatever the actual distances are, as does the difference in outcomes from being hit by a car at different speeds.
Thank you.I'll bet the speed awareness course leaders get sick tired and bored of know it alls claiming exemption due to superior car/driving aids/tyres/skill/driving record/xbox experience.
ETA, picked up some interesting tips on mine.
Edited by PositronicRay on Friday 18th August 11:58
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