Lowering speed limit to 20mph increases injuries and fatalities

[Redlight]

Not a problem though, I just set the car's speed limiter accordingly. Don't think the people stuck behind me appreciated it but fuck them.

I don't have a speed limiter so it takes some determination to maintain 20mph when the car feels as though it is dying!   I know what you mean about people getting annoyed though. We now have 20mph limits on most of the roads around where I live but they're not enforced so anyone staying under or at the limit gets no end of hassle.

[Kim]

Speed limiter on the Leaf doesn't go down to 20, but you don't really need it, as that's about the speed where it starts to sound like you're in a car.

Winding up car wankers by keeping to the speed limit in a 20 zone is one of life's little pleasures.

[citoyen]

20 is the lowest setting on my car's limiter. I never used to use it until I got my speeding ticket, now I use it most of the time. Consider me a born-again anti-speeding zealot.

I look forward to the day when cars are smart enough to know what the speed limit is on a given stretch of road and set the limiter automatically (I'm sure the tech must exist for this already, if not the political will and/or budget to implement it). Although perhaps it's more likely that all cars will be self-driving before that happens.

[ian]

Part of the problem is perhaps the number of over-powered and over-sized cars that litter our roads. Why people need a three tonne, bazillion horse power main urban battle tank to go Sainsbury's or the school at the top of the road, I don't know. All sold on the back on adverts featuring skinny, attractive people speeding unheeded down empty roads. No, dimwits, you'll be queuing to park in an out-of-town shopping centre slowly poisoning your fat bodies. And of course, you'll have to work two jobs to afford the two cars that get you to the two jobs that you don't like, and then when you don't see your kids because you're working all those hours, you can make it up to them by spending the weekend bickering about 'I told you not to drive this way' and you spend your leisure time buying stuff you don't need and can't afford because you've bought those two cars. One of which is possibly an Audi and driving an Audi is pretty much like walking up and down the high street with a placard that reads 'I'm a cunt' because as an Audi driver you are a cunt. Sorry, but it's true. At least there's a teeny chance of redemption for BMW owners.

Anyway, here's the mind of one of those anti-20mph campaigners, pretty much perfectly summarized in an easy to digest format. I think we all regret the deprecation of the <blink> tag.

[mcshroom]

Our site roads at work are 20mph limited, and especially for contractors, speeding where is an instant ban from site (which in most cases effectively means they lose their job), nobody breaks the limits. The Civil Nuclear Constabulary do enforce the site limits*

It feels strange driving (and cycling - we also have to stick below 20 officially) at that speed for a while, but now it's just how it is, and you just get used to how the car feels. In many ways, I think the more these 20mph zones spread around the country, the more that people will get used to them and drive to the limits. For now we are still in the 'war on motorists' sulking phase. What's needed is the police to do a bit of enforcement to make drivers realise they do have to take the limits seriously.


*Partly through boredom - they have also been known to chase unlidded cyclists** on blues and twos!
**Site rule annoyingly is mandatory magic hats - a rule which pretty much killed off our fledgling staff 'site bikes' scheme

[Cunobelin]

Founded it!!!!!

A document from Portsmouth that reflected the claims that is made by the original article.

Headline figure showing increase, total figure showing decrease, and neither statistically significant

The analysis showed the total accident reduction was 13% and the number of casualties fell by 15%. KSI casualty numbers stayed the same whilst KSI accidents increased by 2%. None of these results were statistically significant when compared against national trends.

[Pickled Onion]

Part of the problem is perhaps the number of over-powered and over-sized cars that litter our roads. Why people need a three tonne, bazillion horse power main urban battle tank to go Sainsbury's or the school at the top of the road, I don't know. All sold on the back on adverts featuring skinny, attractive people speeding unheeded down empty roads. No, dimwits, you'll be queuing to park in an out-of-town shopping centre slowly poisoning your fat bodies. And of course, you'll have to work two jobs to afford the two cars that get you to the two jobs that you don't like, and then when you don't see your kids because you're working all those hours, you can make it up to them by spending the weekend bickering about 'I told you not to drive this way' and you spend your leisure time buying stuff you don't need and can't afford because you've bought those two cars. One of which is possibly an Audi and driving an Audi is pretty much like walking up and down the high street with a placard that reads 'I'm a cunt' because as an Audi driver you are a cunt. Sorry, but it's true. At least there's a teeny chance of redemption for BMW owners.

  Is that the poster for Trainspotting 3?

[Cunobelin]

On a roll.... (I found an old drive which I used when I was working with the Council.)

Another summary which was at 3 years. In this case there is a statistical significance claim for the data

This report presents calculations based on the published raw data with allowance for random variation. The first conclusion is that the change in total casualties from 183 (before) to 142.4 per year (after) is statistically significant (P = 0.0005), with non- overlapping 95% confidence intervals. The decrease is a fall of 22%.
Secondly, the change in the killed and seriously injured (KSI) rate from 18.7 to 19.9 per year is not statistically significant (P > 0.5), with 95% confidence intervals that almost completely overlap.
In conclusion:
(1) On the total casualty rate
There is strong evidence that the underlying total casualty risk fell after the introduction
of the 20mph speed limits.
(2) On the KSI rate
The change in KSI casualty rate is well within year-to-year random variation, with large
uncertainties around the estimates of risk, due to the small numbers. Further data is needed before conclusions can be drawn concerning whether the KSI risk is affected by the introduction of 20mph speed limits.

[Cudzoziemiec]

Our site roads at work are 20mph limited, and especially for contractors, speeding where is an instant ban from site (which in most cases effectively means they lose their job), nobody breaks the limits. The Civil Nuclear Constabulary do enforce the site limits*

It feels strange driving (and cycling - we also have to stick below 20 officially) at that speed for a while, but now it's just how it is, and you just get used to how the car feels. In many ways, I think the more these 20mph zones spread around the country, the more that people will get used to them and drive to the limits. For now we are still in the 'war on motorists' sulking phase. What's needed is the police to do a bit of enforcement to make drivers realise they do have to take the limits seriously.


*Partly through boredom - they have also been known to chase unlidded cyclists** on blues and twos!
**Site rule annoyingly is mandatory magic hats - a rule which pretty much killed off our fledgling staff 'site bikes' scheme

I went somewhere with my sister at the weekend which involved driving into the outskirts of Bath. She's used to driving round Bristol, where the limits are all 20, or out in the countryside, and commented how odd it felt to be driving in a town at 30mph. Not that traffic often gets above stationary in Bath, even in the outskirts.

[fd3]

Mainland blah blah 30kph=20mph blah blah.

I think we first need 20mph zones, then we can explain why breaking the law in those zones is a bad thing.  Then we can think about some sort of enforcement.  I reckon many motorists will stick to the limit and many more will be reminded by the flashing “this is your speed” lights.  You can double the motorists sticking to the limit when you include those in the cars behind.
Reminds me that I need to write my councillor (and the candidates in the upcoming local election).
Blah blah.

[hellymedic]

People DON'T stick to <20mph in 20mph zones. The police don't/won't/can't enforce 20mph and illuminated speed signs have little/no effect once they've been in place a few months.

20mph limits are frequently made to be 'self-enforcing', with speed bumps, cushions and chicanes that make life for cyclists hazardous.

Most roads in Camden have a 20mph limit.

In theory.

[Cudzoziemiec]

I do know someone who was fined for 24mph in a 20 zone.

[hellymedic]

Where was this, out of interest?
I really don't think it happens round here!

[Cudzoziemiec]

Bristol. I'm told there were no other circumstances warranting attention, but I'm not entirely convinced.

[Diver300]

http://webcache.googleusercontent.com/search?q=cache:K2cW3dBo1uoJ:eprints.uwe.ac.uk/34851/7/BRITE%2520Bristol%252020mph%2520limit%2520evaluation%2520report%2520final.pdf+&cd=1&hl=en&ct=clnk&gl=uk

Just down the road in Bristol, 20 mph zones appear to work...

FCVO "work". There has been a statically significant reduction in average speeds, 2.7 mph one one measure and 0.8 mph on another measure. If a car travelling in free road conditions at the speed limit has an average of 1 car following who would otherwise go faster, it only needs around 1 in 7 drivers to conscientiously sticking to the speed limits before and after the change to get the 2.7 mph reduction. The rest of the driver can carry on ignoring the speed limit. The fraction needed to achieve 0.8 mph reduction is, of course, much less.

I wonder if the change to 20 mph is just making sure that the conscientious drivers get bullied more?

[Greenbank]

Where was this, out of interest?
I really don't think it happens round here!

The Police don't actively enforce 20mph limits (i.e. they won't park up and sit there with a speed gun) - they save that resourcing for the faster roads - but that doesn't meant they won't deal with someone speeding if they happen upon it, so if you do 25mph+ in front of a Police car in a 20mph limit (and they follow you for the requisite distance, and haven't got anything else to do, etc) then you *may* get pulled over.

Winding up car wankers by keeping to the speed limit in a 20 zone is one of life's little pleasures.

And being tailgated for doing so is rewarded with a drop to 18mph, then 16mph. It's a limit not a target right?

[Basil]

Where was this, out of interest?
I really don't think it happens round here!

The Police don't actively enforce 20mph limits (i.e. they won't park up and sit there with a speed gun) - they save that resourcing for the faster roads - but that doesn't meant they won't deal with someone speeding if they happen upon it, so if you do 25mph+ in front of a Police car in a 20mph limit (and they follow you for the requisite distance, and haven't got anything else to do, etc) then you *may* get pulled over.

Winding up car wankers by keeping to the speed limit in a 20 zone is one of life's little pleasures.

And being tailgated for doing so is rewarded with a drop to 18mph, then 16mph. It's a limit not a target right?

Actually, I've seen the police using a speed gun in Llandysul several times recently.  Possibly because the 20 mph limit is still quite new.
Shame they do it on a road that has reasonable pavements.  I'd prefer they did it on my street.  Particularly the bit near my house that has no pavement on either side where cars whip past my elbow at >30 mph.

Like you, I do enjoy driving in the town with a caravan of cars behind all trying to climb into each others boots. 

[Wowbagger]

The thesis posted in the thread title is clearly a lot of bollux spouted by the carwankers just to try to avoid obeying the law. See also Robert Winston and "cycle lanes increase pollution" carwankerbollux.

[mattc]

Actually, I've seen the police using a speed gun in Llandysul several times recently.

What are they like noe with cycling wrong way down a 1-way? Just asking for a friend, obviously ...

[Basil]

Actually, I've seen the police using a speed gun in Llandysul several times recently.

What are they like noe with cycling wrong way down a 1-way? Just asking for a friend, obviously ...

Why would you need to?  We have roads going in both directions dontchaknow.   

To be fair, when we lived outside Llandysul, I would often cycle the wrong way on Charles Street as a short cut to the café.

[rogerzilla]

The thesis posted in the thread title is clearly a lot of bollux spouted by the carwankers just to try to avoid obeying the law. See also Robert Winston and "cycle lanes increase pollution" carwankerbollux.

They probably do, if there's no modal shift.  Which there won't be, because Britons are fat lazy bastards, cycling is for the gay and the poor, and people have quite remarkable tolerance for congestion so long as they can blame someone else.

[pcolbeck]

Even if some people don't obey 20 limits a lot will. Some people don't obey 30 limits now so should we not have 30 limits? It would be interesting to see what the average speed is in a 20mph zone compared to a 30mph zone I bet its lower. People might drive 35 in a 30 thinking its just a bot over the limit but in a 20 those same people might do 25 with the same logic. I know that they are still speeding but the point is they are driving 10mph slower which is a good thing. Speed limits aren't about enforcing some arbitrary max speed (why 20mph is it massively safer than 19mph or 22mph no its just a convenient round number) for the sake of if but about cutting down on injury and death so it doesn't really matter if a 20mph limit achieves 100% compliance so long as it gets a significant proportion of drivers to slow down.
Every car that obeys they 20 limit or even reduces its speed from 30 to 25mph is making the road a little bit safer.

[sg37409]

4th of 4 phases of 20 mph limit in Edinburgh city becomes in force on 05-March. Can't say I've noticed much difference tbh.
http://www.edinburgh.gov.uk/info/20243/20mph_for_edinburgh/1481/20mph_in_my_area/1

Even if some people don't obey 20 limits a lot will.

IME, its far, far from a lot.  Possibly folks who used to drive at 40 now drive closer to 30, but I only really see a difference in the buses behaviour.  Even they don't like to sit behind a cyclist doing 20mph.

[Jaded]

I drove in Edinburgh last weekend. As an occasional visitor, I thought traffic was noticeably slower.

[Little Jim]

Some people do get caught in the 20 limits it seems...

http://road.cc/content/news/237844-driver-risks-losing-licence-repeatedly-breaking-20mph-limit