New High tech cameras to enforce 20mph roads

morqthana · 21 Mar 2026

motorbiking said:
nope

Modest Speed Reductions: A 2018 Department for Transport (DfT) review of signed-only 20mph limits found a reduction in median speed of less than 1mph.

So in other words 20mph limits have very little effect on journey times, and so anybody complaining that they make journeys take too long is talking complete bllx- it's just a false claim they've seized on to try to disguise the real reasons for their opposition.

Shall we look at some of the other findings from the study?

The majority of residents, non-resident drivers and cyclists (between 69% and 89%) perceive 20mph limits to be beneficial for residents, cyclists and pedestrians

The study shows that 20mph limits are generally supported and there is little call for the limit to be changed back to 30mph;

There is an established positive relationship between vehicle speed and injury collisions – the higher the speed, the more collisions and where collisions do occur, the higher the risk of a fatal injury at higher speeds.

motorbiking said:
Limited Impact on Casualties: A study of a 20mph intervention in Belfast city centre found "little effect" on long-term outcomes such as collisions, casualties, and speed, outside of reducing traffic volume.

Investigating the impact of a 20 miles per hour speed limit intervention on road traffic collisions, casualties, speed and volume in Belfast, UK: 3 year follow-up outcomes of a natural experiment | Journal of Epidemiology & Community Health

A 20 mph speed limit intervention implemented at city centre scale had little impact on long-term outcomes including road traffic collisions, casualties and speed, except for a reduction in traffic volume. Policymakers considering implementing 20 mph speed limit interventions should consider the fidelity, context and scale of implementation.

Belfast was a small-scale scheme, restricted to the city centre, where traffic speeds were already low.

The same report also says

Much larger effects have been demonstrated when 20 mph speed limit interventions are implemented city-wide in comparison to city centre. The example in Bristol has been used by many local authorities to support the introduction of 20 mph limits. Research evaluating the effectiveness of the city-wide 20 mph speed limit intervention in Bristol found statistically significant reductions in average traffic speeds of 2.7 mph, and a reduction in the number of fatal, serious and slight injuries from road traffic collisions, equating to estimated cost savings of over £15 million per year. Similarly, in a city-wide 20 mph speed limit intervention in Edinburgh, evidence highlighted that, following the implementation of the 20 mph policy, a further reduction in collision rates occurred. Specifically, the average number of collisions per month in Edinburgh in 1997 was 165, while in 2019 this number fell to 64.

motorbiking said:
Low Compliance: Studies have noted that in some areas, compliance is poor, with up to 76% of drivers exceeding the 20mph limit in some zones, as reported in a 2024 analysis.

Low compliance is a reason for increasing enforcement in order to encourage compliance, not a reason to abandon 20mph limits. From the first report you referenced:

The most common area of concern across all user groups considered was around compliance, with most focus group and survey participants of the opinion that stronger enforcement measures are needed if 20mph limits are to be effective.

motorbiking said:
City-centre 20mph limits have ‘little impact’ on collisions, casualties and speed, new study suggests

and of course with "every single" 20mph zone claiming 20-30% casualty reduction, we'd expect huge improvements in the fatality rate and total casualties. So where are they?

They are probably in places you refuse to look at.

morqthana · 21 Mar 2026

johnny2007 said:
morqthana said:

Mottie, and at least johnny2007 and aveatry, don't want you to do that.

Click to expand...

Do what?

Let me see if I can help you to understand the post of mine which you quoted.

morqthana said:
IT Minion said:

I try to focus on the more serious issue as a rule of thumb.

Click to expand...

Mottie, and at least johnny2007 and aveatry, don't want you to do that.

So the "doing what" will be "try[ing] to focus on the more serious issue as a rule of thumb".

Do you see it now?

johnny2007 said:
Reduce pollution?!?!
I am no expert, but my experience is this: my former automatic gearbox won't engage third gear until car is over 23/24mph. So going at 20mph the engine is revving at 1300rpm. At 24mph it revs at 1000rpm.
Isn't the engine polluting more at 1300rpm?

The energy consumed by accelerating a car is proportional to the square of the speed gained. So getting to 30mph takes 2.25 times more energy than to get to 20mph (ie 30² compared to 20²). Given that in most urban settings there is repeated slowing down and often stopping for hazards, obstacles, congestion, lights, it is the repeated depletion (braking) and then acceleration to peak speed that uses most fuel. That is why a 20mph limit cycle will require less than half the energy than a 30mph limit cycle for acceleration.

Whilst the sweet spot of the engine in terms of efficiency may make a slight difference this is not significant.

So, the mechanics and physics are quite clear. Smoother driving to a lower limit will always require less energy, less fuel and produce fewer emissions than repeatedly accelerating to a higher limit.

johnny2007 said:
Exactly.
At 20mph, almost everywhere here in west London, I see many drivers playing with their phones and even watch movies.
Too slow is not safer because the same drivers would be paying attention to the road if going at 30, so a pedestrian jumping on the road could be easily avoided.
Better not to be hit than be hit at 20mph.

Any argument along the lines that some drivers cannot manage to drive safely at 20mph is an argument for taking those drivers' licences away.

morqthana · 21 Mar 2026

Odds said:
If you had an electric vehicle then it wouldn't be a problem, would it?

Excessive acceleration and braking will still produce more particulate pollution from tyres and brake pads, and will still increase road wear.

morqthana · 21 Mar 2026

Mottie said:
Comrade Khan's

Using a term like that displays such a high level of bias and antipathy that nothing you say about him or his policies can be taken seriously

Mottie said:
he refused to put out figures showing the so-called reduction in pollution in his expanded ULEZ zones before the mayoral election.

ULEZ expansion August 2023.

Proper year-long monitoring study began September 2023.

Results not available only part-way through the study when the elections were held in May 2024.

FYI - when the study was complete it was found that the reductions were real, not "so-called".

morqthana · 21 Mar 2026

motorbiking said:
Some people are daft enough to believe them.

You might like to think about how many people are daft enough to believe that objections from people like you and Mottie are not driven by political ideology instead of facts and truths.

morqthana · 21 Mar 2026

motorbiking said:
better to not be hit by someone who braked sooner, because they were more engaged in the process.

Better not to have to share the roads with drivers so -----ng useless that they can't pay enough attention to what they're doing.

morqthana · 21 Mar 2026

Deluks said:
Changing a speed limit from 30 to 20 is optional, for the councils.

Maybe it shouldn't be.

Maybe UK-wide the default speed limit for restricted roads should become 20mph. That would be a big help for all the drivers who say that they don't have the mental capacity to cope with having 20mph and 30mph limits.

Deluks said:
Lets not kid ourselves that councils don't make a healthy income from the motorist.

And lets not make the mistake of thinking that councils get money from speeding fines.

morqthana · 21 Mar 2026

Deluks said:
So would you support it being lowered to 10mph to reduce those numbers even further?

Reductio ad absurdum.

morqthana · 21 Mar 2026

motorbiking said:
You do get that we have only had a 6% reduction in the number of people killed on roads in the last 10 years?

You talked elsewhere about some people being daft enough to believe the results of air quality monitoring exercises.

Looks like here you're assuming that everybody is going to be daft enough to not spot that you're dismissing reductions on 20mph roads because those speed limit changes have not had an effect on non-20mph roads.

I'd like you to take these example figures

	Before 20 MPH limit	After 20 MPH limit
Deaths on roads susceptible to 20 MPH limit	100	60
Deaths on roads not susceptible to 20 MPH limit	567	567

and tell us what the reductions in deaths are on 20mph roads and overall.

morqthana · 21 Mar 2026

Scof said:
Where I live there is no need for a 20mph limit because you would struggle to travel at much above 20mph on an 8' wide lane bordered by drystone walling & Hawthorn hedges.

Then a 20mph limit there wouldn't be a problem for anybody, so why oppose it?

morqthana · 21 Mar 2026

It's starting to look as if the refuseniks, having tried cherry-picking data to "prove" that they're right to dismiss 20mph limits, and been caught out and thus failed dismally, are now starting to dismiss all data,

Mottie · 21 Mar 2026

Someone had trouble sleeping last night.

noseall · 21 Mar 2026

morqthana said:
It's starting to look as if the refuseniks, having tried cherry-picking data to "prove" that they're right to dismiss 20mph limits, and been caught out and thus failed dismally, are now starting to dismiss all data,

Correct.

ALL of the data and studies show that fatalities and serious accidents have fallen (some significantly) since the introduction of the 20 MPH limit.

Massive home goal by MBK.

Scof · 21 Mar 2026

Speed does not cause vehicle related incident deaths ( I refuse to call them accidents ). Bad driving causes most vehicle incidents & occasionally this results in death.

As someone who passed their test in the late 70's after 8 lessons I am horrified at the fact that todays young 'uns average 40+ lessons & suffer such a high incident rate in the first few years of driving that their insurance premiums are more than I paid for my first house.

Speed does not kill, abysmal driving standards & pathetic attitudes to fellow motorists does.

noseall · 21 Mar 2026

Scof said:
Speed does not cause vehicle related incident deaths

Scof said:
Speed does not kill

How many stationary vehicles are responsible for pedestrian deaths, v's those vehicles travelling at speed? The speed of the vehicle in a collision is always a factor, regardless of who is driving.

New High tech cameras to enforce 20mph roads

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