LTNs, 20mph etc. Traffic calming, or the war on motorists

Is accurate.

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When I was first a learner (i.e. long before I was a competent driver) 20mph felt like it was as fast as I could safely go, and perhaps it was. There are also some very, very old drivers out there who seem to have recognised that 20mph is as fast as they can safely drive too. Perhaps if 20mph becomes what you’re used to it will also become all you can safely manage ?

If you have a reference for the numbers I’d be interested to see them. The figures I remember are for speeding in 30 zones which said “If you hit a child at 30mph there’s a 90% chance they’ll survive. If you hit one at 40mph there’s a 90% chance they won’t”. Cases don’t come much more compelling than that. But the speed itself can’t be the whole story. I recall a tragic case where a man killed his wife by taking the handbrake off and then being unable to stop the car rolling down their drive and crushing her. It can’t have been doing more than a few miles an hour but still it was lethal. I wonder if 20mph might be safer than 30mph not because the speed difference significantly changes the harm but because at 20mph more people have time to react if a child runs into the road unexpectedly ?

Road Safety factsheet: 20mph Zones and Speed Limits - RoSPA

According to data from The Royal Society for the Prevention of Accidents, at traffic speeds of 30-40mph, the risk of pedestrian death as a result of a collision with a vehicle is 5.5 times more likely than at speeds between 20-30mph.

However, a three-year research project by Queen’s University Belfast claims 20mph speed limits across the city have made little difference to safety, but did reduce the volumes of traffic.

The data was collected over 76 streets in the centre of Belfast prior to the introduction of the 20mph rollout, and then one and three years after they were installed.

That information was then compared with data collected from nearby streets where the 20mph are not in place and similar roads elsewhere in Northern Ireland that had retained their speed limits (30-40 mph).

Analysis of the data revealed that when compared with areas that had retained their previous speed limits, the new 20mph limits led to minimal change in short or long-term outcomes for road traffic collisions, casualties, or speeding.

In total, road traffic collisions fell by 3% and 15%, respectively, over the one and three-year periods after the policy took effect.

Over the same time frame, casualty rates fell by 16% and 22%, respectively. However, researchers said these reductions were not statistically significant.

(Source: Do 20mph speed limits reduce the number of car crashes and casualties? | RAC Drive )

Sadly the true motivation may simply be an earner, (Cameras earn money, speed bumps don’t) Educating kids in particular (70’s Tufty club style) or making driving tests more stringent both cost but don’t earn. Cynical I know, looking at several studies 20 MPH is not the harm reduction people may hope it is.


I agree with you here- with an important caveat- this stuff needs to be carefully planned.

Busy estates with lots of children and vulnerable road users; yes.

As a blanket regulation, no.

The amount of near misses I have observed is staggering. People are fucking mad. To get past my Milkfloat, they boot it and with the blistering acceleration of modern cars, if the worst should happen, the closing speed will be incredibly high.

Greater London is of course not representative.

But I do see lots of cunty ‘driving’ in London.

I agree in densely populated streets, nr schools etc 20 MPH makes sense but rolling it out strikes me as skater shot at best oppressive at worst.

I think I’ve said here before, it’s all 20 mph here.

The only camera is just before the blind corner that precedes the nearest bus stop to the very big school.

Kids congregate in large numbers, generally arse around and wander into the road.

I assume that the camera was sited very deliberately.

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Sensible planning here then. Just a memory- from 20 years ago… Fuck. I am an old cunt…

Anyhoo; a small section of a busy estate changed from a 30 to 20mph limit.

Excellent. Buses were generally compliant. Regular reminders were broadcast via the Cab Radio as it seemed some complaints came in regards to speeding buses. Fair enough.

But motorists would continue to overtake in dangerous places.

This stopped with some ‘Environmental Engineering’ in the form of evil speed cushions and speed tables…


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The safety argument at 20, particularly with children and the reduction of the risk of them landing on their head is one thing. As a pedestrian living in a town that has a 20 road through the middle there is a marked improvement in the lived experience. Simple things like crossing the road is much easier, not just for the pedestrian but also for the driver. With a two second gap between cars most able bodied peds can cross the road and the next driver won’t need to slow down. At 30, usually driven at 35, then you have to wait, and wait and when you do step out the next driver will be braking.

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i am keen on dropping from 30 to 20 for road noise reasons as we live on a main road - i suspect there will be a marked drop in DBs when everything is electric and the speed limit is 20 (we have a school opposite too so suspect we will get a 20 zone at some point regardless)

walking along the main road into town is so unpleasant I dont do it (go via side streets instead) so totally agree with your point Bob

unfortunately not, due to AVAS reasons

thank the septics for pushing this through globally

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When they brought in 20mph in Edinburgh it felt really slow and required effort and concentration. Years down the line it feels natural and more relaxed. It’s more pleasant all round.

Lots of people were very angry at the time. They were angry about the trams too, and those are quite nice.

It’s more pleasant than it was, but if I want to cycle somewhere with the kids I still have to put a lot of thought into the route and there will invariably be stretches that I really don’t feel comfortable with. That doesn’t seem right to me :slight_smile:

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EVs are much quieter on my road. It’s a 30 limit, just changed to 20, and you can really tell the difference between an EV and an ICE car. I think it’s the lower frequencies.

What I’m really looking forward to are electric buses coming to St Albans though!

Yes. I think that’s what I was speculating about. We get used to the way things are, and the way things used to be then feels more extreme. Every couple of years I get an extension ladder out and clean out the gutters on my two-storey house. I’m OK with ladders - mine has a spreader which keeps the top really stable and I’m careful in other ways too. But after two years not using anything taller than a step-ladder that first climb up to the gutter is a sweaty experience. I cling on. I don’t look down. I have become less capable at this activity. Fortunately my ability returns quite quickly. After an hour I’m much more confident. But I was wondering whether 30mph felt ‘too fast’ to drivers who’d become (re)conditioned to 20mph in part just because of the conditioning, or whether it really was the case that they had never actually been safe at 30mph.

Roads are used for lots of things and outings with the kids are a perfectly legitimate one of them (I speak as someone who cycled an 11-mile round trip to and from work more days than not for 25 years or so). But if I was a home care worker who had to divide my time between driving and caring for frail/vulnerable people I might regret being forced to spend more time driving and less time caring, and so might the people I care for. As with most changes in life, there will be winners and losers.

… It is people – cyclists, walkers, pedestrians, schoolchildren – who have been under assault from the way in which cars have been allowed to dominate our lives …

And there I was thinking that cars were just inanimate objects and that everything they did was controlled by a person, or people, inside them.

… The very concept is a daft jibe that looks good in a headline but makes no sense whatsoever on closer examination …

Keep saying that Christian. Keep saying it.



I was about to say, but the article already makes the point

The decision was made despite a survey showing most residents in affected areas wanted the measures to stay.

And the recent study by the University of Westminster (IIRC) suggests that overall LTNs discourage rather than divert traffic.

So that’s a :frowning_face: from me.