Safe Speed Forums

and as for anything Al Gore has to say: Read This

Philip, I have just read the associated report, and I agree with the majority of it, but I am a little disappointed about the section implying support for 20mph speed limits.

As Paul will be able to demonstrate the statistics about injuries and vehicle speed are at best totally misleading, because the frequency of collisions that actually occur AT the speed limit is incredibly small, for the simple reason that the motorist will normally brake. There are also plenty of examples where vehicles travelling within a 20 mph speed limit have been involved in fatal collisions. The main problem with 20mph zones is that typically (in the UK) they are implemented through the addition of a complete barrage of additional traffic control measures, such as more humps, chicanes, lights and other distractions to motorists. Have a look for sotonsteve's threads about how they are being implemented in Southampton through an excess of traffic lights and other controls.

It doesn't really fit into a report that is in the main about removing artificial restrictions and letting people take responsibility for their own actions. The whole point is that there shouldn't be a speed limit, any more than there should be "no parking" lines, give way signs or pedestrian crossings. Everybody should be moving around using "COAST", and the vehicle speeds will be naturally moderated to the safe speed for the conditions at that time. The fact that this is generally a lower speed than the speed limit is just a consequence of the change of mentality where drivers have to look out for themselves, and not through external authoritarian imposition.

On the other hand, common sense dictates that lower-speed zones have a lower speed limit precisely because they are more dangerous and accidents are more likely. The laws of physics quite clearly demand that the faster you smack into something, the more damage is done.

I don't see how anyone could possibly argue that driving into a pedestrian at 30 is safer than at 20.

Really interesting article. Are there absolutely no rules at all? No right of way or anything?

The point is that running into a pedestrian, even at 20 mph is very rare indeed. The misuse of the data is leading to solutions to non-existent problems. Unfortunately the unnecessary solutions come with side effects. The critical flaw is the assumption that crashing at 'free travelling speeds' is commonplace. It isn't.

How do we know? Well, for example, there are nowhere near enough dead children. Around 1/1000th of the number expected. See this PR from 29th September:

========================================
PR372: Road safety culture shock stage two. Not enough dead children.

news: for immediate release

It is perfectly clear that people all over the country are re-evaluating their
opinions about road safety policy following revelations yesterday and today.

But we have only just begun back on the road to real road safety.

Television advertisements tells us (quite correctly, as it happens) "If you hit
me at 30 there's a 20% chance that I will die. If you hit me at 40 there's a
20% chance that I will live."

Department for Transport data published yesterday [1] tells us that 11,000
child pedestrians were injured in built up areas (30mph AND 40mph speed limits)
in 2005. We we should expect that more than 20% of those child pedestrians were
killed. Right? That's 2,200 dead children.

But reality is entirely different. 47 child pedestrians were killed in built up
areas, amounting to 0.47% of the total. That's one fiftieth of the implied
claim.

The real world behaviour that saves the children isn't 'sticking to the speed
limit' if it was we would have killed thousands. The real world life saving
behaviour is drivers slowing down in areas of danger and braking before impact.

But this is just the tip of the iceberg. In the real world, many minor crashes
are unreported, many more take place with no injury and are unreported and
countless thousands of incidents take place where appropriate driver behaviour
ensures that the child isn't hit at all. So we end up with something like:

Built up areas:

11,000 Child pedestrians injured and reported
20,000 Child pedestrians injured and unreported (estimate)
20,000 Child pedestrians hit but not injured (estimate)
200,000 Child pedestrians involved in 'near misses'. (estimate)
-----------------------------------------------
250,000 total incidents resulting in 47 deaths.

It doesn't even matter if the estimates are not very accurate. It is OBVIOUS
that a great many incidents take place with very few deaths because of drivers
responding to the situation ahead. This 'driver response' is at the true core
of road safety.

But if the DfT implied claim were true we would have 50,000 dead child
pedestrians, not 47.

And it doesn't even stop there, because a significant but unknown proportion of
the deaths are due to 'rogue drivers' - possibly disqualified, in stolen cars,
blind drunk, unlicenced, underage or whatever. The risk mitigation behaviour of
an 'ordinary' driver is even more effective.

Paul Smith, founder of the Safe Speed road safety campaign
(www.safespeed.org.uk) said: "The Department for Transport calls it their
'20,30,40 message' I call it deliberately misleading. They think it justifies
speed camera policy, I think it damages road safety by forcing road users to
concentrate on the wrong safety factor."

"They trot out this rubbish because they are welded to a false belief system.
Let me tell them right now that false beliefs will not save lives."

"Department for Transport is not fit for purpose."

<ends>

Notes for editors
=================

[1] RCGB 2005 published yesterday (see table 24):
http://www.dft.gov.uk/stellent/groups/d ... 612588.pdf
==================================



Until society has a proper grip on the factors that save something like 999/1000 it would be extremely unwise implement policies that change them (those factors). But that's exactly what we're doing and that's exactly why I'm here. It's why the forum exists.

Or let me put it this way - the real world isn't anywhere close to the place where alterations in speed limits will make a difference to child pedestrian mortality. If even 5% of child pedestrians involved in incidents were dying then the speed limit changes could make a difference. But it not 5% it's about 0.02%.

_________________
Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

Firstly,
Secondly, I'd rather drivers didn't hit pedestrians at all.
But if they've got their eyes glued to their speedos whilst navigating humps, chicanes and build-outs, the driver is paying less attention to the surroundings and is not spotting and anticipating hazards...

_________________
Pecunia Prius Equitas et Salus

This, IMO, is VERY true, EXTREMELY well written and POWERFUL.
As far as I'm concerned, people who really care about road safety (i.e. systematically ensuring that casualty figures are at a minimum) should read this bit slowly, carefully and repeatedly until they understand it.
Yes, it requires a small amount of brain power and a greater attention span than that of a 5 year old, but this is important.

But this is something that doesn't get mentioned - the fact that even with the extra driver loading, most drivers find time to look for hazards / feet under parked car /mother with pram, one in tow and one loose.
Perhaps again as i said in another post - could it be that experience copes with recognised hazards (the subconcious/lizard brain) and the consious is busy with new problems??

Crashes happen when those systems are overloaded or neglected and FAIL.

More load means less margin from overload, more chance of neglecting an essential and more critical events leading to more crashes.

_________________
Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

Agreed - ,but have we looked at the overload/ OVERSTRESS / FAIL situation - perhaps we all have tyhe potential to overcome the overload situation ---but then agin we are asking drivers to go beyond training and experience.

I think shared spaces are an excellent idea, and they will work, without a doubt

I had to take issue with this bit of green rubbish though:

Where do these people live? Mars I think. Agreed, large sports bikes are not particularly fuel efficient, however, with the advent of Euro III (from 2007), emissions and noise are far more tightly controlled. Commuter class Euro III motorcycles on the other hand can easly achieve 60-70 mpg, and scooter class can achieve 100 mpg or more. They are normally very quiet.

As to the crap about endangering road users, where the hell did they dig that little nugget from? The majority of powered two wheeler accidents are single vehicle (especially in the sports bike category), most of the others are normally of the "sorry mate, didn't see you" type accidents.

_________________
"Are you sh**ing me?"
"John Spartan, you are fined one credit for a violation of the verbal morality statute."

SafeSpeed: Interesting stats, but you side-stepped the point of the quote. Impacts may rarely happen at 20 in a 30 zone, but if the speed limit were 20 and drivers stuck to it, surely the number of accidents would decrease and those that did still happen would take place at an even lower speed.

I live in Germany and the speed limit in residential areas is also 30, but 30 kph (18 mph, I think). It's certainly a very different experience to walking around in England. It's quieter and easier to cross the road, and the cars just have to stop at the next set of lights anyway.


I think the idea was to get people onto buses and bikes rather than motorbikes. By road users, I assume they mean the riders themselves. Buses, cars, bikes, heck even a unicycle is probably statistically safer to ride than a motorbike.

I didn't sidestep anything. The problem with 'just reducing the speed limit' is that you have to use the driver's brain as an agent. You would have to be very certain that you were not changing the vital responses at the same time as the speed. There are about 6 real world problems...

- Maintaining 20mph requires a lot of speedo checks and attention diverted.

- Driving at 20mph is likely to be pretty boring, which tends to lead to lower concentration levels.

- A developing situation when a driver is driving to the speed limit requires a 'mode switch' from legal driving to responsive driving. Since these two use different parts of the brain, there will be some mode switching overhead.

- Drivers tend to like to maintain risk levels, so driving at 20mph instead of 30mph, may mean closer following, more aggression or less attention.

- 20mph zones tends to give pedestrians a false sense of security. It seems safer, but it's still deadly.

And all the while this stuff is going on we're working on a factor that's only significant in 1 in 1,000 incidents. BUT we're affecting ALL the incidents.

Anyway, average crash severity is HIGHER in 20mph zones than 30mph zones. Until we know exactly why that is, I'd treat 20mph zones as potentially lethal. See: http://www.safespeed.org.uk/pr116.html

The bottom line is that road safety is a psychology subject, not a physics subject.

_________________
Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

Probably, I would prefer to sit on a bus wasting my day, next to a stinky person getting chewing gum on my clothes, or pedalling all the way to work (10 miles).......
I tried the bus once, and decided that I do not have 2 1/2 hours to waste of my life every day, compared to 30-40 mins car/mc travel.

So until there is a public transport system that can whisk me to the other side of Swindon in 15 minutes, you won't get me on there. On the other hand, I would use public transport (or cycle) if I worked in the town centre - thats a no brainer!

_________________
"Are you sh**ing me?"
"John Spartan, you are fined one credit for a violation of the verbal morality statute."

The answer that makes most sense is that 20mph limits are found in places with the greatest risk of accidents and a larger proportion of children. I agree that you should treat such zones as potentially lethal, but I don't like the way you imply they're more dangerous than 30mph zones somehow because of the lower speed limit.

It's a preposterous idea, but I dare say that a speed limit of 20mph on the motorway would reduce fatalities to practically nil (other than through boredom) given the safety measures in place.

The conclusions fit the statistical data and my understanding of the real world driving process. Nevertheless it's IS a risky conclusion on existing evidence. Equally other conclusions are as risky or riskier.



Motorway limits of 20mph would kill loads. Some as they lose faith in the speed limit and crash into those that kept their faith. Some as they fell asleep through boredom and ran off the road. Some because they lost faith in official road safety and took risks on roads that were not so stupidly restricted.

The point is that we MUST treat road safety as a system founded in psychology.

_________________
Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

Sorry I didn't respond sooner: got sidetracked by work, but I'm finding this discussion very interesting.

I agree that drawing any conclusion from the statistics is risky without more info, but at least the theory I forwarded (that 20mph are inherently more likely to be the scene of accidents) has some basis in logic and common sense.

Your suggestion that it simply has an adverse effect on drivers' concentration/attitude smacks of a high-speed agenda to my mind.

The suggestion that motorways would be deadly with a 20mph is also as preposterous as the idea of implementing it. I often travel on the Autobahn, where the majority of vehicles travel at between 70 and 100mph. A minority of those crazy Germans in their big BMWs and Mercs, however, bomb up and down the same roads at 150mph (fast German motors other than Porsches are electronically limited to 150mph). This leaves us with the same difference in speed we'd have if most traffic travelled at 20 and the law-breakers at 70+, yet the Autobahns have not proven to be deathtraps, and the majority are unlit with only 2 lanes.

The boredom factor is a result of the nature of motorways, not the speed. While travelling faster does require much more concentration, it's the monotonous nature of motorways that lead to boredom-induced accidents, not the speed. Travelling at 20mph in a car, you'd have a hard time killing yourself unless you drove into something explosive or off something really high.

I agree that there is a lot of psychology involved in traffic management. The original subject of this topic is a wonderful example, but how do you get drivers to carry that attitude and concentration onto other roads? How do you make them aware that all roads bar motorways are, essentially, shared-spaces, where pedestrians and cyclists should be expected? Minor roads without pavements or lights look like shared-spaces anyway, but few drivers treat them as such.

Not that I agree with you because I've done a lot of high speed motorway driving in Europe without getting bored but if you're travelling slower you're going to be on the motorway for longer and therefore far more likely to fall asleep.
Now if you were forced to do 20mph then your journey is going to take 4 times as long (at EU speeds). How many more people do you think you be dozing off, never mind how many of them would be attempting to do something else to occupy their minds because 20mph on a motorway is painfully slow.
As for being unlikely to die at 20mph (someone please verify this) don't the majority of fatalities occur in 30mph zones at speeds below the limit?

Being realistic, the 20mph casualties tend to be Pedestrians, and they are relatively infrequent on Motorways.

Although it's the dangers of high speed traffic that enables us to keep pedestrians off. With traffic at 20mph, we'd have calls to treat motorways as playgrounds. (And I'm not kidding.)

_________________
Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

Could motorway boredom be reduced by making the distance between lines, lights and cat's eyes random rather than a fixed value?