A car travelling at 200mph is no more likely to crash than a car at 20mph.Having a crash is not related to speed

You are either trolling or you have some very weird ideas about how physics works! 😯

Probably, but if we’re discussing speed cameras (we weren’t initially, but there you go) then if they’re not in that 16%, speed cameras are unlikely to do anything to stop such accidents. Losing control due to excessive speed is quite likely to be totally unrelated to the speed limit (I did that a couple of times when young and more reckless, both whilst travelling under the speed limit).

Have a read of the list, a lot of them are very hard to enforce.

Sure, but as you pointed out there is a combination of factors, and there will almost always be factors other than the hard to control ones – factors which can be reduced through a combination of training, education and enforcement. We know that 84% of fatalaties don’t have speeding as a factor, but almost all of them will have some other form of negligent driver behaviour which could be improved.

speed cameras are unlikely to do anything to stop such accidents. Losing control due to excessive speed is quite likely to be totally unrelated to the speed limit

Agreed on both counts.

But likewise how do you legislate and enforce laws about someone going excessively fast, but not over the limit?

We’re talking about fatalaties here, which tend to be investigated very thoroughly. I think they’re likely to have solid information in the vast majority of cases and suggesting that some drivers are speeding but not reported as such in the accident stats is idle speculation with no basis in fact

from a home office report describing a national study using serious pedestrian accident cases:

Only incidents that were attended by a qualified collision investigator were deemed
suitable for inclusion in the study. To prevent any possible bias over the data
selected, the collision investigator attending the scene made an independent
decision as to the suitability of the case for inclusion in the study based on the
criteria listed below. They were then asked to complete a comprehensive data
collection form.

In total, 101 cases were reported as potentially being suitable for the study.
Detailed examination of the evidence showed that critical data was missing from
some of the submissions.
Examples of these types of omissions included;
Unable to establish vehicle speed at impact
Point of impact/pedestrian rest unknown
Pedestrian throw displacement not measured
In total 30 cases lacked the detail required to carry out further analysis but 71 cases
were found to contain sufficient evidence to be analysed in detail.

Some attempts at “better” modelling from previously reported and tried cases (granted, paper is 2003, FWIW)

… Greatrix’s example, indicates that the posterior
distribution of the vehicle’s initial speed is centred at about 45 mph (72 km/h), and that a probable range for the initial speed is between 35 mph (56 km/h) and 55 mph (88 km/h).
The posterior probability that the vehicle was travelling at or below the posted speed limit of 30 mph (48 km/h) is essentially zero

[quote]In this case the posterior probability of the vehicle’s initial speed is centred at about 73 km/h, with a probable range being between 60 km/h and 90 km/h.[/quote]

the initial speed of vehicle #2 was most probably around 92 mph (148 km/h), and the
bounds of a 95% credible interval for this speed were 86 mph (141 km/h) and 99 mph

So in those speed kills ads, when they say that you are X% more likely to kill the kid at 33mph than 20mph – does that not indicate that speed kills?

For the hard of thinking, this CLEARLY does not mean that it’s okay to hit kids as long as you are going slowly. I am arguing from the position that some accidents are inevitable, but

1) Lower speeds mean you are more likely to be able to stop in time and avoid the accident.
2) Lower speeds mean that if you do hit the kid, he or she is more likely to be okay.

In this scenario, the kid runs straight out from behind a wall, and is not visible to the driver at all even if the driver is looking. So no matter how great a driver you are all you can do is hit the brakes. The kid is much more likely to survive if you are going slower in the first place, as a precaution.

GrahamS – Member

Yes of ALL accidents

Sorry for being vague Graham, it was 4% of KSIs.

Where is that 4% figure from sbob?

RAS50001 has “Exceeding speed limit” as a contributory factor in 16% of Fatal and 7% of Serious Accidents.

It only drops when you add in Slight Accidents, which gives an overall figure of 5% for All Accident types.

The 4% figure was exceeding speed limit as primary cause, not just contributory.

But where is it from?

I don’t think anything in RRCGB data or the STATS19 form attempts to define the primary cause of an accident.

My internet connection is in and out, I’ll trawl the depths of Pistonheads for links but it may take a while.
Bear with.

Turns out it was the one third lie, not two thirds. Found a thread with a DfT link but it is old and no longer works. Quotes 5% rather than 4%.

http://forums.xpowerforums.com/archive/index.php/t-33401.html

Searched for “Road Casualties Great Britain 2005” and there is some good data out there, but not exactly what I was looking for.

I’m quoting from memory, but have no desire to deceive.
I remember discussing it years ago on pistonheads, but my free Post Office wifi isn’t liking it at the mo.

Okay so I dug up the RRCGB 2005.

It’s not available in the National Archives (yay for crappy government websites!) but it is available via web.archive.org

Your man in that post says “See stats on page 7 (exceeding speed limit = 5%)”

So looking at the Contributory Factors report, page 7, we see a table broadly similar to what is now called RAS50001:

And yes that 5% is for “Exceeding speed limit” recorded as a contributory factor in ALL accident types. (Same as 2014).

For Fatal Accidents the figure then was 12% (4 percentage points less than 2014)
For Serious Accidents it was 7% (Same as 2014)

Also interesting to note that “Going too fast for conditions” was a factor in 17% of fatalities in 2005, but only 11% in 2014.

Perhaps this change could be due to lowering speed limits so that what was “too fast” in 2005 is now “speeding” in 2014?

Regarding 20 zones, that twisty was moaning about earlier, here is a longitudinal study published in the BMJ:

Effect of 20 mph traffic speed zones on road injuries in London, 1986-2006: controlled interrupted time series analysis

Abstract Results: The introduction of 20 mph zones was associated with a 41.9% (95% confidence interval 36.0% to 47.8%) reduction in road casualties, after adjustment for underlying time trends. The percentage reduction was greatest in younger children and greater for the category of killed or seriously injured casualties than for minor injuries. There was no evidence of casualty migration to areas adjacent to 20 mph zones, where casualties also fell slightly by an average of 8.0% (4.4% to 11.5%).

Conclusions: 20 mph zones are effective measures for reducing road injuries and deaths.

If a stretch of road changes from 40mph to 20mph then were the majority of drivers travelling down there at 35mph before the limit change reckless? Or if not, then how is travelling at 35mph after the 20mph limit is in force more reckless than when it was a 40mph limit?

It’d be pretty unusual to go from a 40 down to a 20 but yes the folk doing 35 after that change are reckless.
Why? Because there are now drivers (like me) obeying the limit and doing 20, so going at 35mph introduces a pretty big speed differential and increases conflict. [/quote]

That isn’t a good justification because I am not suggesting that they would be driving at 35mph up somebody’s arse. There are a couple of better reasons I can think of but on the whole I see it as the actual risks of driving at 35mph have not changed as a result of the speed limit being lowered.

spending money installing a wide area 20mph limit rather than looking at where the casualties are, what caused them, and what could be done to remove the causes.

“Good news, now that your child is dead we can finally get that speed bump we’ve been asking for.”
Why wait for casualties and react after the event?
The 20s Plenty style campaigns are about local residents choosing to lower the limits on their own streets. Shouldn’t they get a say? Seems like they are pretty well placed to decide what they want.[/quote]

You are missing my point which is that I think that if there is e.g. £100k to spend on highway improvements in an area I think is often better to spend that on things that resolve issues that are known to be causing casualties, rather than spending it on 1000’s of 20mph signs because that is the current political flavour of the month.
Local residents are obviously well placed to decide what they want but are not necessarily equipped on knowing what they need. They will usually have good knowledge on the local issues, but not on what the best solution to those issues are or how those issues relate to safety risks. Enter 20s plenty who campain for 20 mph limits from signs only without any of those pesky road humps, because that is exactly what most residents WANT. Except what residents NEED for safer roads, is actual lower vehicle speeds, which is not achieved by slapping up 20mph signs, there is a discrepancy between what residents want and what they need.

And there are reasons beyond casualty numbers to install 20 limits: slower, quieter, more liveable streets encourage kids to play outside, encourage people to ride bikes, encourage folk to shop locally and generally make the place a bit nicer

Agreed, but I would say ‘for lowering vehicle speeds’ rather than ‘to install 20 limits’, because depending on how it is implemented a 20mph limit won’t necessarily actually lower vehicle speeds.

Regarding 20 zones, that twisty was moaning about earlier, here is a longitudinal study published in the BMJ:

You really are taking the biscuit GrahamS. I did not bemoan 20mph zones at all. In fact I have wholeheartedly recommended a few in my time.
What I am against is slapping in a wide area 20mph limit without putting any thought into it. Or to summarise it in another way, I don’t like the idea of campaigning for 20mph areas that are of far lower quality than the ones which created the statistics you’ve quoted.
With few exceptions, 20mph limits installed in london on or before 2006 included engineering measures to reduce speeds (e.g. humps), they were often implemented alongside other engineering measures to improve safety (e.g. double yellow lines at junctions, new/improved pedestrian crossings, etc). They were also generally put in areas where an assessment identified above average existing rate casualties where speed was a contributory factor.

Some people use reports of previous 20mph zones to justify the implementation of wide area 20mph limits using signs only. However, I do not believe it is valid to draw this comparison because:
[list]
[*]Signs alone have very little actual impact of vehicle speeds unless done in conjunction with enforcement – often the local police won’t do 20mph enforcement although the tides are shifting on this a bit.[/*]
[*]Signs only schemes don’t deliver the benefits that resulted from other safety engineering measures. When looking at previous 20mph schemes it is difficult/impossible to split out what casualty reductions result from the speed reduction part of the scheme vs the other engineering measures. [/*][*]Reducing speeds in areas where speed is not a significant cause of casualties will not yield the same results as reducing speeds in areas where speed is a significant cause of casualties.[/*]
[/list]

I repeat, I am not against 20mph zones at all. However, I think they work best where the environment creates a gap between the drivers perception of safe speed, vs the actual safe speed and, are implemented in a way that actually reduces traffic speeds.
In general drivers drive at what they perceive to be a safe speed but are sub-consciously using relatively limited criteria to determine this, clear road width, forward visibility, obvious hazards/features ahead, demarcation from opposing traffic, etc. When comparing traffic-calming free neighbourhoods those with wider straighter roads have higher traffic speeds than those with narrow roads. Also, those with wider straighter roads have higher casualty rates than those with narrow roads, basically the wider clear width fools people into thinking the road is safer than it actually is. Also, I re-iterate that sticking up 20mph signs has virtually no impact on those speeds, actual enforcement or engineering measures are required to reduce the speeds.

I see 20’s plenty as doing 3 things:
[list][*]They are promoting the implementation on 20mph zones using signs only. These alone have virtually no impact[/*]
[*]They are encouraging community engagement/social change, this has little impact[/*]
[*]They are encouraging the police enforcement of 20mph zones. Increased enforcement would have impact.[/*] [/list]
In summary 20’s plenty are essentially selling the dream of a safer place rather than actually delivering it, unless, they succeed in increasing police enforcement of 20mph zones, this brings things full circle back to the OP.

BTW GrahamS I don’t get why for that that Table 2 GB 2005 ‘Driver/Rider or Reaction’ cat is 65% for fatal although its sub-cats add up to only 47%, and for Serious the cat total is 60% when the sub-cats add up to 63%. I know you didn’t create the figures but if you have an explanation I’d appreciate it as I am flummoxed.

You’re going to have to explain how those factors mean that the driver was speeding and yet the policeman chose not to put that down as a factor (the factors not being exclusive makes it less likely that the driver was speeding despite not being reported as a factor rather than more).

The contributory factors recorded are the view of the investigating officer but they generally try to follow evidence rather than a hunch when recording the factors – it is easier to prove from the evidence that somebody failed to give way, or lost control of their vehicle; rather than that somebody was going to fast for the conditions, this is much more subjective. When considering accuracy note that for non fatal accidents it is not uncommon for the collision position co-ordinates to be wrong by 15m or so. Fatalities/suspected fatalities are looked into in greater detail than other accidents so are more likely to have the evidence available to record that the speed limit was exceeded. Although up to 6 factors may be recorded, generally only 1-3 factors are put down.

A large portion lot of fatalities involve vulnerable road users such as pedestrians, cyclists, mopeds, subsequently a lot of fatalities are where this type of conflict is most likely to occur i.e. 30mph area, at junctions.

I hate it when people quote these HC figures as fact when surely anybody with half a brain knows that they are ancient and and over-conservative. Speed campaigners do games at school fetes where people plant flags of what they think the braking distances are and then these are compared with the ‘actual’ figures from the HC. This doesn’t target the people who have enough of a brain to realise that the HC figures are BS but are still under-perceiving the implications of speed. It’d be far more effective (and fun) IMHO to put in a bit more effort, clear out a section of the car park and have parents do some real braking tests in their cars.

Tool lazy to read all the posts properly and duplication never hinders anyone here anyway.
3 reasons why cameras are not good idea.
1) The big brother idea. I sort of agree in that where I go is my business but I also see the virtue in that it may help catch undesirables, inhibit stupid driving and catch speeders. etc
2. The potential for cyclist to be included and a demand for their licencing.
3. Crap and fast drivers are bloody selfish.
I would love to see them. Shove them on street lamps.
They need to be attached to a different penalty system though. I see no reason at all why current driving fines should not have at least two zeros stuck on the end. Ensure that the income go fund the cameras and processing and I bet it pays. When it stops paying switch them off. Leave it a year until all the f..wits have started speeding and switch them on again.

How could you include cyclists in a speed camera initiative if bikes don’t have speedometers?

How could you include cyclists in a speed camera initiative if bikes don’t have speedometers?

In the UK speed limits do not actually apply to bicycles, except in Royal Parks.

Some cyclists have actually been hit by speed tickets in Richmond Park, so the lack of requirement for a speedo does not appear to be a defence for for speeding.

It is a valid concern that if people implement an absolute rule of speed on the roads then the law could change to apply to bicycles too. This would nark me a bit, I started going to Richmond Park less frequently because dragging on the brakes when just to stay below 20mph down the hill is annoying.

If it hasn’t been said already, anyone who’s said they’ve passed the IAM test and this gives them the ability to drive faster than speed limits where appropriate; wasn’t paying attention to the course instructor. IAM is a charity, and will very quickly loose that status if it’s found the it’s instructors are advocating breaking the law, and as a great many of them are ex coppers, they tend to take a dim view anyway.

So, consider yourself a shit driver if you’ve had advanced training, and use this as a reason to exceed posted limits at your discretion.

Having the ability isn’t the same as actually doing it.

I’m certain that I have the ability to safely drive above the speed limit given the right situation and conditions, and I expect many others have a similar or even greater ability to do so. However I rarely do so these days.

And to preempt the obvious reply; take police pursuit drivers as an example, or emergency response drivers in general. When they’re rushing to an accident scene, are they recklessly endangering others? Or, y’know, is it because they are more highly skilled and trained?

Passing the IAM test doesn’t give you the right to exceed the speed limit. But it almost certainly gives you the ability to (and I would assume also, education as to reasons not to).

nickc – Member
If it hasn’t been said already, anyone who’s said they’ve passed the IAM test and this gives them the ability to drive faster than speed limits where appropriate; wasn’t paying attention to the course instructor. IAM is a charity, and will very quickly loose that status if it’s found the it’s instructors are advocating breaking the law, and as a great many of them are ex coppers, they tend to take a dim view anyway.

So, consider yourself a shit driver if you’ve had advanced training, and use this as a reason to exceed posted limits at your discretion.

But the Police themselves have argued (successfully) that their “special skills” need to be taken into account when accused of driving at excessive speed.

I would argue that the cops themselves are a special case. and as a society we allow them leeway to do the job they do, and accept the risk that that brings? They’re a small proportion of the road traffic overall.

My instructor was of the opinion that road craft was all about observation, anticipation, and information, combine all those, and journey times are reduced, drivers and passengers are less stressed, and as you’re making better decisions, you make better progress*, you shouldn’t need therefore to drive impatiently or faster than the speed limit as you’ve planned your journey anyway.

He suggested that there was a discussion to be had on making Mways variable speeds, the motorway at 3am is a different place to a motorway at 6pm, but he was a very strong advocate of speed limits on ALL other roads. His reminder to me was that Highways agencies don’t like putting unnecessary road makings down, as their budgets are tight, therefore the more road signs/markings there are, the more reason there is to put them there in the first place (and the reason is unlikely to be that the HA want to spoil your day by slowing you down), and therefore the more one needs to pay attention to whats going on. A 40 sign on an otherwise legal 60 road? There’s probably a reason for that…

*hateful expression, but that’s just me

EDIT. My instructor was all about the continuous dialogue. I had to calmly and rationaly be able to give a running commentry on the road, the speed limit the activity of other road users and my actions. It was hard and took an awful lot of concentration. He would often then ask me what make of car was 2 cars behind me, or had pulled into a side road a couple of minutes before. It was very hard to do all that, and drive faster than the speed limit!

twisty – Member

But the Police themselves have argued (successfully) that their “special skills” need to be taken into account when accused of driving at excessive speed.

Getting an IAM certificate is slightly different to high-speed driver training given to emergency services.

The title of your link is misdirecting though, on reading it that case was about his use of speed to chase another car, and the police argued they should not be punished for dangerous driving in that circumstance. The report notes he was (rightly) convicted in a previous case when using (extremely) excessive speed for no valid reason.

A car travelling at 200mph is no more likely to crash than a car at 20mph.Having a crash is not related to speed

Aaaand this is why people die.

Based on the arguments of some in this thread I’m going to go and buy an £8000 mountain bike, do a couple of skills courses with nice certificates and I’m pretty sure I will beat Aaron Gwin and be world champion next weekend. I’ll think of you thankfully as Danny Hart sprays his champagne onto me.

Blimey twisty – I thought my posts were lengthy!
Okay a few retorts and comments:

I see it as the actual risks of driving at 35mph have not changed as a result of the speed limit being lowered.

You can’t say that because you have no idea what might have changed on the road and surrounding area that prompted the limit to be dropped so dramatically.

For example it could be that a new primary school has opened which abuts the road.

Ultimately where would you draw the line? Are you happy to drive every road at what the speed limit used to be on it, because at some point in the past that limit was deemed appropriate?

20 limits… bemoan.. bemoan 😉

I think we are more on the same page than you realise here.

I’m fully aware that 20 limits that consist purely of signs have much less of an impact than ones that are backed by proper road engineering.

Because they are not enforced and lots of drivers think they know better than the posted speed limits which are there for no good reason (those impressive reductions in casualty figures must, of course, be due to other drivers being slowed down. Not experts like them).

One interesting

aspect I’ve heard about through the local cycle campaign is that many of those road features that passively enforce speed limits (pillows, narrowed and raised junctions, etc) have “design speeds” inthe guidance which means often they can’t be put in until the road is already a 20.

BTW GrahamS I don’t get why for that that Table 2 GB 2005 ‘Driver/Rider or Reaction’ cat is 65% for fatal although its sub-cats add up to only 47%, and for Serious the cat total is 60% when the sub-cats add up to 63%. I know you didn’t create the figures but if you have an explanation I’d appreciate it as I am flummoxed.

I didn’t screen grab the entire table, there are a couple more lines for in that category: “Swerved” (7%) and everyone’s favourite “Loss of control” (35%)

The individual factors should always add up to equal or more than the category total (since one accident/casualty can have multiple contributing factors in the same category).

A large portion lot of fatalities involve vulnerable road users such as pedestrians, cyclists, mopeds, subsequently a lot of fatalities are where this type of conflict is most likely to occur i.e. 30mph area, at junctions.

Yep.

In RRCGB 2014, around 37% of Fatalities were on 30mph or less roads.

446 fatalities were pedestrians, 113 were cyclists.
Together they make up 31.5% of the 1,775 recorded road deaths.

I hate it when people quote these HC figures as fact when surely anybody with half a brain knows that they are ancient and and over-conservative.

Yeah I think they definitely contribute to the notion that speed limits and safe gaps between cars are out of date and should be ignored.

The trouble with the “speed kills” propaganda is that unless cars do not comply with the basic laws of physics this statement is totally untrue.

Irony of ironies. A post denying the laws of physics, which itself claims to be defending them.

Speed never has and never can kill, no single person has ever died from going too fast.

And that’s probably the single most pedantic and ridiculous comment on this thread.

I see it as the actual risks of driving at 35mph have not changed as a result of the speed limit being lowered.

You can’t say that because you have no idea what might have changed on the road and surrounding area that prompted the limit to be dropped so dramatically.[/quote]
Even if I am the traffic engineer who is processing the traffic order/works for the change in speed limit and I know that the motivation for the change is purely political rather than any change of circumstance?

One interesting aspect I’ve heard about through the local cycle campaign is that many of those road features that passively enforce speed limits (pillows, narrowed and raised junctions, etc) have “design speeds” inthe guidance which means often they can’t be put in until the road is already a 20.

Nah that is bollox, they are probably re-iterating excuses given to them by the authority. One may install traffic calming features on a >20mph road* but they need advanced warning signs e.g.

Based on 2002 TSRGD this one doesn’t need illumination unless >30mph road or trunk road so it is not onerous to install (illumination requirements may be further relaxed in the new TSRGD).
*Actually the warning sign requirement refers to being inside/outside of a 20mph zone (there is a difference between a 20mph zone and a 20mph limited road) but again things may have changed with the 2016 TSRGD which I have not read yet.

no single person has ever died from going too fast.

In other news, no one has ever died from jumping off a tall building.

(though some people have died from the entirely unrelated impact shortly after).

Even if I am the traffic engineer who is processing the traffic order/works for the change in speed limit and I know that the motivation for the change is purely political rather than any change of circumstance?

Yes the risks are higher if you go the same speed in a now lower speed limit zone. As I said in a previous comment other users now consider that area to be slower so may expect you to be going slower and may act accordingly, potentially causing an accident that would not have occurred if you were actually going slower.

Yes the other person should not presume, but if we have learnt anything from this thread is that no-one can rely on anyone else to do what we would expect of them.

Unintended consequences are a bitch.

Speed never has and never can kill

I take it you lot are also pro-gun rights, because guns don’t kill people, do they…

STATO – Member
Getting an IAM certificate is slightly different to high-speed driver training given to emergency services.

The title of your link is misdirecting though, on reading it that case was about his use of speed to chase another car, and the police argued they should not be punished for dangerous driving in that circumstance. The report notes he was (rightly) convicted in a previous case when using (extremely) excessive speed for no valid reason.
Nah he got off the previous charge too. Either training is a valid mitigation for safety risk at speed, or it isn’t. I bet Police drivers really are not anything special, most people with a race licence probably have better high speed handling skills.

On the other hand, it does annoy me that there are cases where police officers have quite obviously been taking the piss (not on emergency call, no flashers/siren on) and got away with it just because they are the police and they have ‘special training’.

I take it you lot are also pro-gun rights, because guns don’t kill people, do they…

Guns don’t kill people.

Bullets on the other hand…

(-:

nickc – Member

If it hasn’t been said already

I make sure I mention it every time, but it is often overlooked. 🙂

i forgot to weave this one in earlier

So given the opinion seems to be that a 200mph car IS more likely to crash than a 20mph one shall we just rename Bloodhound to Bloodbath and be done with it?

Think about it for a second.

Saw this review of a Focus RS in today’s Metro and thought I’d post it here as it speaks volumes about our attitudes to speed :

Woo.. It can stay within the speed limits if you like grandad, but if you want some fun then select the Track or Drift mode and “push it to your limit”. 🙄

I’m sure the journalist would argue that, of course, they meant on a private race track – but there’s not even a pretence of that in the article.

^ DM sure has changed its tune since the Carlton Lotus eh?

Think about it for a second.

I don’t even need a second.

The trollseeking question that I put was:

If speed was irrelevant in the context of accidents happening then someone doing 200mph through a busy residential street would be no more likely to crash than someone doing 20mph. Do you believe that to be true?!?

Frankly anyone that does believe that shouldn’t be allowed a driving license.

This thread still going?

What’s happened?

Last time I looked it seemed like common sense was going to prevail…..

But then again this is STW…!

I must have missed your original point then, I saw a stripped out version that gave some sense to my comment.

As you were then…