Should CTC join campaigns for 20mph?

[EdinburghFixed]

Since casualties are recorded by age, gender and mode, even the national audit office would be able to provide a meaningful number of child pedestrian casualties! I'm pretty sure that 17 year old drivers can be isolated from the data

The point about 20mph zones being a bit like bike helmets is well made. It's blindingly obvious that helmets must save lives, until you look at population level data and find that the same number of people are being killed whether the helmet wearing rate is 80% or 8%. I would be amazed if there is a clear consensus, without cherry picking, on the effects of 20mph zones either.

Food for thought.

[PBA]

The point about 20mph zones being a bit like bike helmets is well made. It's blindingly obvious that helmets must save lives, until you look at population level data and find that the same number of people are being killed whether the helmet wearing rate is 80% or 8%. I would be amazed if there is a clear consensus, without cherry picking, on the effects of 20mph zones either.

I've just done a google search for some statistical data on the safety of 20mph zones - without success. Unless my search terms were particularly daft, this is surprising as 20mph zones have been around for many years in trial form.

A 20mph zone, even if it can be shown to reduce injuries, could not be expected to reduce them to zero. If our target is zero, then we need to see 20mph as an interim measure quickly followed by 15, 10, 5 and finally 0mph!

The alternative is to accept that there is a cost in human life for our current lifestyles. I'm guessing that most people would accept the possibility of the death of a few others in order to not have to adapt to the change in circumstances. Likewise I suspect that wide adoption of 20mph zones would not take long to be seen as the "norm".

Personally I see little problem with 20mph on estate roads, and imagine that this make those areas a nicer environment to live in. That sounds like a good enough reason, even if we still end up mowing down the kiddies...

[NUKe]

The minister quoted a Transport Research Laboratory study of 250 20mph schemes across Britain, which found that, after the limit was reduced, crashes fell by 60 per cent, child casualties by 67 per cent and average speeds by 9mph.

look by to my ealier post for the link to the TRL and the research

[kwackers]

The minister quoted a Transport Research Laboratory study of 250 20mph schemes across Britain, which found that, after the limit was reduced, crashes fell by 60 per cent, child casualties by 67 per cent and average speeds by 9mph.

look by to my ealier post for the link to the TRL and the research

Reducing the limit by 10mph produces a speed reduction of 9mph! That's fantastic (if it's true). It's also flies in the face of every other piece of research I've ever seen which showed that a 10mph reduction usually results in a drop of 4-6mph.
I'd also add that whilst I often see people driving at 30 in a 30 I've never seen anyone drive at 20 in a 20 - with the exception of where there are physical reasons for not being able to speed.

I can't help but think someone's playing with figures here.

(Incidentally your TRL link doesn't work, have you got another that does?).

[Ben Lovejoy]

The speed reduction does seem to completely different to every other limit reduction measurement I've ever seen.

But then these sorts of figures are very often nonsense. Take a road with unusually high casualties one year, take any step you like (speed limit reduction, camera, speed-humps, whatever) and the following year the rate drops to the usual average for that road and you claim success for whatever you did.

[George Riches]

Put 20 mph in the search box at http://www.trl.co.uk to find the reports.

E.g. "Review of traffic calming schemes in 20 mph zones" 1996
"Review of 20 mph zones in London Boroughs" 2003

The big reductions in traffic speeds were where physical measures had been applied. Without siginificant physical measures, only 1 mph reductions in average speeds were measured. However the proponents of 20 mph as a general limit hope that where a zone covers a wide area significant speed reductions will occur without bumps.

In the report about London Boroughs,the estimated reduction in cyclist KSI casualties was 30-50% . Such a dramatic reduction is surely of interest to the CTC as an organisation representing cyclists.

[kwackers]

Put 20 mph in the search box at http://www.trl.co.uk to find the reports.

E.g. "Review of traffic calming schemes in 20 mph zones" 1996
"Review of 20 mph zones in London Boroughs" 2003

The big reductions in traffic speeds were where physical measures had been applied. Without siginificant physical measures, only 1 mph reductions in average speeds were measured. However the proponents of 20 mph as a general limit hope that where a zone covers a wide area significant speed reductions will occur without bumps.

In the report about London Boroughs,the estimated reduction in cyclist KSI casualties was 30-50% . Such a dramatic reduction is surely of interest to the CTC as an organisation representing cyclists.

As I thought, earlier in this thread I mentioned that physical methods of speed reduction were more effective than the tin plate variety...

What I'd like to see now is what difference does the tin plate actually make? If you put physical obstructions in place but leave the limit has 30 do you get the same benefits?
I'd argue the 1mph difference of the tin plate system is of no real value and allowing for the complex interactions that occur could make things worse. On the other hand it would appear that a physical barrier does work (as you'd expect) and may in fact be just as effective without changing the numbers on the plate.

[George Riches]

[...] it would appear that a physical barrier does work (as you'd expect) and may in fact be just as effective without changing the numbers on the plate.

Some vehicles are not greatly affected by many "physical" measures - so there won't be much to stop drivers of those continuing at 30 mph, if the legal limits weren't changed.

On the other hand "physical" measures have a number of drawbacks - some vehicles are much more affected by them than others, they cause problems for emergency vehicles and buses. Many cyclist aren't too happy with them (e.g. if gaps are left in humps to allow buses to pass at quicker than walking speed, motorists swerve about trying to take advanatge of them).

[CREPELLO]

Put 20 mph in the search box at http://www.trl.co.uk to find the reports.

E.g. "Review of traffic calming schemes in 20 mph zones" 1996
"Review of 20 mph zones in London Boroughs" 2003

The big reductions in traffic speeds were where physical measures had been applied. Without significant physical measures, only 1 mph reductions in average speeds were measured. However the proponents of 20 mph as a general limit hope that where a zone covers a wide area significant speed reductions will occur without bumps.

In the report about London Boroughs,the estimated reduction in cyclist KSI casualties was 30-50% . Such a dramatic reduction is surely of interest to the CTC as an organisation representing cyclists.

As I thought, earlier in this thread I mentioned that physical methods of speed reduction were more effective than the tin plate variety...

What I'd like to see now is what difference does the tin plate actually make? If you put physical obstructions in place but leave the limit has 30 do you get the same benefits?
I'd argue the 1mph difference of the tin plate system is of no real value and allowing for the complex interactions that occur could make things worse. On the other hand it would appear that a physical barrier does work (as you'd expect) and may in fact be just as effective without changing the numbers on the plate.

My views have assumed a similar take on the right mix of measures adopted, that the 20 signs alone would have minimal affect. BUT, I still think that the widespread adoption of a lower limit in more urban areas can underline the basis for a new social attitude and a policy on reducing traffic speed. The advantages outways the disadvantages in my view. I'm afraid that arguments like drivers staring at their speedo's all the time don't carry much weight. I notice that the Save Speed website (a campaign group run primarily by drivers from what I can tell - their principle tool for reducing road casualties is driver education) goes on about this danger - I haven't found this argument anywhere else. I would concede that sometimes cars may be in conflict with the faster cyclists more often, but this is swings and roundabouts and you as a fast cyclist will be able to hold the primary position far more often. If you're slower the cars will overtake, where's the problem?

On the subject of child casualties that Ben Lovejoy alluded to, I think you may have this wrong Ben. Of the statistics I've seen (see link below) I haven't found any that group children as up to age 18. So arguing that the statistics on child casualties is exaggerated is misleading I think, to say the least.

Looking at the DfT paper on Pedestrian road casualties for 2007 http://www.dft.gov.uk/pgr/statistics/datatablespublications/accidents/casualtiesgbar/suppletablesfactsheets/pedestrianfactsheet07.pdf I note ironically that the section on contributory factors in accidents (page 6) shows that the most factors causing an accident were attributed to pedestrians.
This suggests that no matter how carefully a driver things he's driving, unpredictable movements by pedestrians will cause collisions to occur. IF though, the speed limit is reduced then the factor of unpredictability is reduced from increased reaction times and less stopping distances required.

[kwackers]

Some vehicles are not greatly affected by many "physical" measures - so there won't be much to stop drivers of those continuing at 30 mph, if the legal limits weren't changed.

On the other hand "physical" measures have a number of drawbacks - some vehicles are much more affected by them than others, they cause problems for emergency vehicles and buses. Many cyclist aren't too happy with them (e.g. if gaps are left in humps to allow buses to pass at quicker than walking speed, motorists swerve about trying to take advanatge of them).

But, physical methods do reduce speed whereas it would appear changing the speed limit doesn't.

[kwackers]

<snip>

What we have though is the idea that just sticking a 20 plate over lots of areas isn't going to have much effect (at least for a while), that leaves traffic calming.

Now like George Riches, I too am not that keen on traffic calming - it does have lots of drawbacks, however if you want to reduce traffic speed then at least in the short term you have no other real option.
It also removes the idea of a 'cheap' option that people earlier in this thread seemed to think, since one thing traffic calming isn't - is cheap.

On the other hand why not push for an improvement in car design? Without government forcing their hands there's no way manufacturers will implement them since they do tend to 'uglify' cars and thus make them harder to sell compared to non pedestrian friendly cars.
As an indication some technology (crumpling bumpers, pedestrian airbags) have a similar effect to reducing the impact speed by 20mph! What is there not to like? All it requires is the political will to force the manufacturers hand.

[CREPELLO]

....It (traffic calming)also removes the idea of a 'cheap' option that people earlier in this thread seemed to think, since one thing traffic calming isn't - is cheap.

On the other hand why not push for an improvement in car design? Without government forcing their hands there's no way manufacturers will implement them since they do tend to 'uglify' cars and thus make them harder to sell compared to non pedestrian friendly cars.
As an indication some technology (crumpling bumpers, pedestrian airbags) have a similar effect to reducing the impact speed by 20mph! What is there not to like? All it requires is the political will to force the manufacturers hand.

I have constantly advocated a government policy that compels councils to introduce 20 limits alongside measures such as traffic calming over a phased period, because of the inherent cost of implementing the policy properly (as well as minimising the tabloid/voter antagonism that could occur with a fixed date roll out).

ON IMPROVED CAR DESIGN, yes we can push for that as well, but of itself it runs the risk that if we pursue that as a primary way of reducing pedestrian casualties, it will give the driver the sense that he is driving a 'pedestrian friendly' vehicle, thereby giving the illusion of enhanced safety, which he/she will compensate for with increased speed.

[SP]

I wholeheartedly agree - traffic at speeds above 20mph is threatening to vulnerable users principally because in metal boxes at that speed people can barely make human contact - that's why people have completely different manners when driving - seeing the world and the people in it as merely in their way, to paraphrase.

Incidentally, I note the opening phrase on the home page of this ie. CTC's website which reads: We are the country’s largest group of people on bikes. Our mission is to make cycling enjoyable, safe and welcoming for all.

I personally am glad they have joined campaigns for 20mph.

Regards

Steve

[Ben Lovejoy]

On the subject of child casualties that Ben Lovejoy alluded to, I think you may have this wrong Ben. Of the statistics I've seen (see link below) I haven't found any that group children as up to age 18.

Either they are using a different definition for pedestrians, or this has changed in the last few years.

I note ironically that the section on contributory factors in accidents (page 6) shows that the most factors causing an accident were attributed to pedestrians.

Why is that ironic?

It also suggests that the best way to reduce pedestrian casualties is by pedestrian education.

[thirdcrank]

I think the main thing it shows is that the RT 19 'accident' stats collected by the police are, for organisational reasons, often victim blaming. As in "never allege an offence you cannot prove (nowadays apparently extended to cannot be bothered to prove.") Most things a driver might do to cause a collision are offences where for pedestrians they are not.

Apart from that, give somebody an additional, onerous duty, especially the dreaded 'paperwork' when it's something they consider to be pointless and it's unlikely to be done well.