20mph limits: pros and cons?

[DulwichLondoner]

Lowlander Wrote:

> Those against the 20mph limit are using

> questionable data and processes.

>

> Those supporting 20mph limits are using the proper

> processes consistent with those used in medical

> studies.

Ehm, I'm not so sure.

The PDF from the brake website is just unsubstantiated propaganda.

Lambeth Council, on its official webpage about the 20mph limits, did not deem it appropriate to present the slightest bit of evidence in support of the measure: https://www.lambeth.gov.uk/parking-transport-and-streets/streets-and-roads/lambeth-goes-20mph . They present a bunch of numbers, but, as the authors of the BMJ article rightly claim, you can't infer anything from just a few numbers.

I explained my reservations about the BMJ article so I'm not going to repeat them, other than to stress that they are very similar to the criticism of the statistician in your Telegraph article about the lack of a control group (where on earth was the control group in the BMJ article? How do we know the 20 and non-20 areas compared are, in fact, comparable)?

Totally unsubstantiated claims, like those of the lady at the beginning of this video of the 20 is plenty campaign, that this will increase property values and solve all kinds of problems:

remind me of the propaganda of the over-enthusiastic North Korea news anchor lady:

:)

The Rospa link does have more material. I don't have time to go over it now, but I will soon.

There is something very basic I fail to grasp. The campaign claims that the difference to journey times during rush hour won't be huge, and I tend to agree. So how on Earth can lower limits possibly account for something even only remotely close to the 40ish% reductions in collisions claimed in the BMJ article??? Do most collisions happen in those very rare and very short periods when motorists can actually reach 30mph? Do they mostly happen at night when roads are emptier (and fewer pedestrians are around)? For example the Telegraph article you mentioned says that:

"only 15 per cent of fatal crashes and 5 per cent of all accidents are caused by speeding."

Let's not forget that a part of these speed-related accidents is caused by behaviour which, however despicable, is unlikely to be affected by lower speed limits (e.g. drunk driving).

Can you understand my confusion?

PS I wonder if this was the decision-making process:

:)

[rendelharris]

Here's an interesting extract from another Telegraph article (full article here http://www.telegraph.co.uk/motoring/road-safety/8702111/How-do-accidents-happen.html):

"It has been an eye-opener," says project manager Neil Greig, of the IAM. "Not just in terms of what causes an accident but in terms of dispelling some of the popular myths. For instance, if you look at Government campaigns they seem to say that speed is the number one problem. But illegal speeding ? when drivers exceed the posted limit ? accounts for only 13.9 per cent of fatal accidents. A bigger cause [15.9 per cent] is going too fast for the conditions ? entering a bend too quickly, for instance ? when you might well be under the actual speed limit."

But the biggest cause of road accidents in the UK today? The statistics are quite clear on this and it's "driver error or reaction". It's listed by police as a factor in more than 65 per cent of fatal crashes and the heading covers a multitude of driving sins many of which you're probably on first-name terms with. Topping the charge sheet is failing to look properly (the Smidsy factor ? "Sorry mate, I didn't see you', relevant in 20.5 per cent of fatals involving driver error), followed by "loss of control" (34 per cent) which, says Greig, often means leaving yourself with "nowhere to go" after entering a bend or other situation, too quickly. Other errors include "poor turn or manoeuvre" (12 per cent) and "failed to judge other person's path or speed" (11.6 per cent.).

Second biggest cause of fatal accidents, to blame for 31 per cent, is the "injudicious action", an umbrella term for "travelled too fast for the conditions' (15.9 per cent of those labelled injudicious), "exceeded speed limit" (13.9 per cent) or "disobeyed give-way or stop sign" (2.1 per cent)?

Third culprit in the daily gamble on who lives and who dies is "behaviour or inexperience" (28 per cent), which covers faults such as "careless, reckless or in a hurry" (17 per cent), "aggressive driving" (8.3 per cent) and "learner/inexperienced" (5.3 per cent).

The fourth main category is "impairment or distraction" (to blame for 19.6 per cent of fatal accidents) covering "alcohol" (a factor in 9.6 per cent of fatal accidents) and "distraction in vehicle" (2.6 per cent).

So, "only" 13.9% of people killed are killed by people exceeding the speed limit. But 15.9% are killed by people going too fast for the conditions - so that's already nearly 30% of fatalities caused by excessive speed. No breakdown but it's fair to assume that at least some of those "too fast but under the limit" fatalities were caused by drivers in 30MPH zones taking bends too fast (one of, to my mind, the big arguments for 20MPH zones: yes that stretch of road might be safe for 30MPH, but how many drivers have the skill and judgement to slow properly for that bend/junction ahead? I'm continually braking/swerving out to avoid drivers for whom the stop line appears to have come as a complete surprise and who brake at the last second. Polite note to drivers by the way, you're supposed to have the whole of your vehicle behind the stop line, not your front wheels resting on it, or as is becoming all too common, having it under your bum with six feet of bonnet sticking into the road). Then 20.5% of accidents involve "Smidsy" - again it's surely obvious that faster speeds lead to less careful observation of the margins and less time to react. Then there's 17% caused by "careless, reckless or in a hurry" and 8% "aggressive driving" - safe to assume speed plays a part in a lot of those as well.

So there's more to excessive speed than just people exceeding the speed limit. In an ideal world everyone would be a good and responsible driver and know not to take that bend/approach that junction/pass that playground at 30MPH even if the limit says they can, in the real world traffic needs slowing.

[Dogkennelhillbilly]

DulwichLondoner Wrote:

-------------------------------------------------------

> rendelharris Wrote:

>

> > No, moving traffic offences are the likes of

> > blocking stopboxes, making illegal turns,

> driving

> > the wrong way up one way streets etc, speeding

> > offences are separate and the revenue goes to

> the

> > treasury.

>

> I see - my bad, then.

>

> Do councils still somehow get the money back, i.e.

> is that money reallocated back to road safety,

> etc, or can the government use it for whatever it

> wants? In other words, do councils really have no

> financial incentives whatsoever in speeding

> tickets? I hope you'll forgive my scepticism :)

Sorry - we are talking about Southwark here. It sold off a tenth of central London and managed to lose money. Do you really think they're capable of pulling off some intricate multistage revenue generation scheme?

[malumbu]

To return to the subject ie speed. Would scrapping speed limits and allow drivers to take sensible decisions about appropriate speed be a way forward? From the stats above I expect not.

What is missing is a mechanical failure. I expect due to the MOT, the greater reliability of cars, warning ligths etc not a big issue any more. Certainly was when I first drove as was packing 7 into a mini. The good old days.

So it was (1970s or 80s). Seven students cram into a mini on their way home from a party. You'd better drive Dave, your too peed to sing. Well it used to amuse me anyway.