Speeding Does Not Cause Accidents

[AA999]

emmaT2014 said:

A factor yes, but not necessarily a 'contributing factor' in the cause of the collision.

But shirly 'factor' is the same as 'contributing factor' no?

ie.
- speed was a factor in the collision
- speed was a contributing factor in the collision

they both mean the same thing, yes? .... a factor is such that it already 'contributes'.

[blueg33]

AA999 said:

emmaT2014 said:

A factor yes, but not necessarily a 'contributing factor' in the cause of the collision.

But shirly 'factor' is the same as 'contributing factor' no?

ie.
- speed was a factor in the collision
- speed was a contributing factor in the collision

they both mean the same thing, yes? .... a factor is such that it already 'contributes'.

No the cause could be driving with a blindfold on. But if tere was no movement, ie no speed at all then their couldnt be a collision even with a blindfold on. Speed is ALWAYS a factor but in many cases is not a contributory factor.

Edited by blueg33 on Monday 20th October 16:28

[AA999]

OTBC said:

Third time:

Among the TRL reports the ABD does not like to cite is TRL 421, "The effects of drivers' speed on the frequency of road accidents" published in March 2000. Unlike TRL 323, this study was designed to discover the speed-crash relationship.

The authors looked at 300 sections of road, made 2 million observations of speed and got 10,000 drivers to complete questionnaires. They found that

the faster the traffic moves on average, the more crashes there are (and crash frequency increases approximately with the square of average traffic speed)
the larger the spread of speeds around the average, the more crashes there are
Significantly for the ABDs argument, and for the rest of us, they also found that:

drivers who choose speeds above the average on some roads tend also to do so on all roads
higher speed drivers are associated with a significantly greater crash involvement than are slower drivers
For these reasons they conclude that the speed of the fastest drivers (those travelling faster than the average for the road) should be reduced. The study confirmed what is described as a 'robust general rule' relating crash reductions to speed reductions: for every I mph reduction average speed, crashes are reduced by between 2-7%. More specifically, the crash reduction figure is around

6% for urban roads with low average speeds
4% for medium speed urban roads and lower speed rural main roads
3% for higher speed urban roads and rural main roads
To put the dangerousness of speed into perspective, how many drivers care about or would notice a 2mph reduction in their average speed? Yet, averaged across the entire road network, a mere 2mph reduction in average speeds would prevent more than 200 deaths and 3,500 serious casualties a year. The authors of TRL 421 suggest that this target (about a sixth of the overall speed related casualty figure) is a 'reasonable minimum' to aim for. More importantly they use it to show "the sensitivity of accident numbers to a small change in average speed". In other words, speeds that might not seem excessive. Speeds that TRL323's methodology wouldn't even record.

Ibid.

Lower speeds mean fewer collisions, injuries and deaths. Basic common sense.

Technically speaking though its not usually the speed itself that causes a crash to initiate, if automated vehicles (cars, trains etc.) travelled at 150mph, and were programmed to not crash then the speed would not be an issue.
Its the human factor that causes crashes. The person behind the wheel making a mistake. (OK, there are also random mechanical failures but these to an extent can cause a crash at any given speed or any given system of vehicle).

A balance has to be struck to keep human controlled vehicular transport effective enough whilst keeping road safety acceptable enough.


Comparing road death numbers to that of alcohol related deaths for example; 1,486 road deaths in 2013 (from the ONS document posted earlier in thread) with 8,367 alcohol related deaths in 2012 # , a factor of 5.6 larger....... now look at how many times and the vigour at which in every town and city across the UK in which you see drunk and disorderly behavior being addressed by the law, and note which of the two situation has more focus.... I would argue that road deaths and especially speeding were focused on because many people through pressure group advertising tactics and their pure concentration on speed alone view most accidents as being caused by speeding (which in the real world is not the case).

1. source : http://www.ons.gov.uk/ons/rel/subnational-health4/...

Edited by AA999 on Monday 20th October 16:12

[OTBC]

jaf01uk said:

And who I suspect has maybe 1 and possibly 2 profiles active in this very discussion?

For those (Emma or Steve) who claim that speed enforcement is not being used as the magic bullet for road safety can I refer you to the siting of average speed cameras on the A9 in Scotland. A road with an infamous reputation for frustration driven overtakes and head on collisions as a result, (where the average speed is already below the limit over the length of the enforcement area) the fix according to the politicians? Yup you've guessed it, average speed cameras for over 80 miles at massive cost, I am soooo looking forward to the reduction in accidents with that brilliant idea! Not!!
Gary

I'm not Emma or Steve, you seem a bit paranoid. Cameras are sited according to ACPO guidelines, politicians have nothing to do with it, which politician are you claiming is responsible for the A9 cameras?

[emmaT2014]

AA999 said:

Technically speaking though its not usually the speed itself that causes a crash to initiate, if automated vehicles (cars, trains etc.) travelled at 150mph, and were programmed to not crash then the speed would not be an issue.
Its the human factor that causes crashes. The person behind the wheel making a mistake. (OK, there are also random mechanical failures but these to an extent can cause a crash at any given speed or any given system of vehicle).

A balance has to be struck to keep human controlled vehicular transport effective enough whilst keeping road safety acceptable enough.


Comparing road death numbers to that of alcohol related deaths for example; 1,486 road deaths in 2013 (from the ONS document posted earlier in thread) with 8,367 alcohol related deaths in 2012 # , a factor of 5.6 larger....... now look at how many times and the vigour at which in every town and city across the UK in which you see drunk and disorderly behavior being addressed by the law, and note which of the two situation has more focus.... I would argue that road deaths and especially speeding were focused on because many people through pressure group advertising tactics and their pure concentration on speed alone view most accidents as being caused by speeding (which in the real world is not the case).

1. source : http://www.ons.gov.uk/ons/rel/subnational-health4/...

Edited by AA999 on Monday 20th October 16:12

The balance is struck; its sits at or close to the speed limits and not beyond them.

It makes little sense to exceed them hence the abandonment of the 80mph speed limit for the motorway. For a saving of only 5 minutes for every 50 miles of travel. What would be the benefit especially when you consider that it is rare to experience a 50 mile journey at the limit? Add in a short section of congestion and the benefit is totally lost.

There is a balance however some drivers are not satisfied with that; as it happens not the majority.

[Foppo]

Some of the roads I have driven on in Linconshire are diabolical.Cars stuck behind slow lorries and drivers taking changes overtaking.It isn't always speed what kills, the design of road systems and the authorities thinking speed camaras are the end and be all.If there are regular accidents on some roads there is a big problem.

[vonhosen]

Phatboy317 said:

vonhosen said:

And it could be somebody with a less developed sense/appreciation of speed having to make the judgement. It's not only about you, it's about catering for all & creating a framework that achieves the best compromise.

You evidently didn't read my comment properly.

If someone judges that they're going to take 3 seconds to cross the road, and they correctly judge the car to be doing 30mph, and that they'll have sufficient time to cross without causing the car to slow down, the car would be 3 * 13.33333 = 40 metres away.
So, even if they've misjudged the speed and the car is actually doing 40, it will be able to stop in time

However, if they underestimate the time taken to cross the road, let's say 1 second instead of 3, then they're in trouble even if the car's doing 30.
OTOH, if they over-estimate the time taken to cross the road, to, say, 6 seconds, then the car will be 80 metres away, and will be able to stop in time even from 60mph.
However, they could also misjudge the distance, in which case they could also be in a lot of trouble.

So there's a lot of factors they could misjudge besides speed, which are at least as significant, so why place so much emphasis on the one factor?

And, in any case, given the short distances involved - it's unlikely that someone would deliberately step out in front of a car that's almost on top of them, it seems far more likely that the pedestrian has failed to notice the approaching vehicle at all, or is completely heedless of the traffic, rather than just being a case of simple misjudgement of the speed/time/distance.

Also, from the driver's perspective, the distances involved are very small indeed.
Given that you're supposed to be able to read a numberplate from 20 metres, at the bare minimum, it's reasonable to expect that a driver ought to be able to see a pedestrian who may be about to cross the road from sufficient distance to be able to slow down comfortably in good time.
Of course, the pedestrian might run out from behind a parked car, for example, but if that's a possibility then even 30mph is probably way too fast under those circumstances, and the driver really ought to have paid attention to the parked cars at the side of the road and slowed down to a commensurate speed in good time.

But simply driving according to the speed limit is analogous to walking in a permanently stooped over position, in case you should encounter a low doorway - the danger being that you stop looking out for low doorways, and end up banging your head on one which is lower than usual.

The danger to pedestrians and other vulnerable road users is the false sense of safety which they, as well as drivers, get from very low speed limits, causing them to take less care.

vonhosen said:

I believe the math is (assuming all else being equal with a good reaction time by the driver in each case of 0.67secs & a deceleration of 8.5m/s-2, which represents a fairly good modern car with ABS)

That the 30mph car will take 19.56m to stop & the 40mph car will take 30.79m.
The result of that is that at the point in the road that the 30mph car has come to a stop the 40mph car will still be doing 30.89mph (which will hurt).

That's because when you increase speed you are much further down the road before you even hit the brakes & a lot of your speed is lost in the last metres, which results in high impact speeds at the position in the road slower vehicles have already stopped. Fairly modest increases can result in high impact speeds.

This has been covered on other threads - suffice to say that comparing stopping distances like that tells you nothing, because if your speed was any different then you would not have been at the same place at the same time.

It was rubbish when it was covered on the other threads as well then.

No-one was saying you left home at the same time & would be there at 40mph or 30mph when the object appeared in front of you. In the comparison it's that you were at that point doing one of those different speeds when the object appeared & the resulting differences in outcome as a result of that speed in those circumstances.

[Mill Wheel]

emmaT2014 said:

Accidents - Injuries
Accidents - Injuries
Accidents - Injuries
Accidents - Injuries
Accidents - Injuries
Accidents - Injuries
Accidents - Injuries
Accidents - Injuries

I repeat the two because they are quite different.

ACCIDENTS - Speed has a LOW observed contribution to the cause of accidents
INJURIES - Speed has a HIGH observed contribution to the cause of injuries

The reduction of speed in collisions will have a significant impact in reducing the number of fatal and serious injuries.

Accidents - Injuries
Accidents - Injuries
Accidents - Injuries
Accidents - Injuries
Accidents - Injuries
Accidents - Injuries
Accidents - Injuries
Accidents - Injuries

They are quite different.

Edited by emmaT2014 on Monday 20th October 12:47

You had to edit that?

So how slow do you have to go in order to eliminate serious injuries?
http://www.newsexpressngr.com/news/detail.php?news...
Obviously not slow enough, as this occurred during a parking maneuver.

So how slow do you have to go in order to eliminate serious injuries?
http://www.newsexpressngr.com/news/detail.php?news...
Obviously not slow enough, as this occurred during a parking maneuver.

So how slow do you have to go in order to eliminate serious injuries?
http://www.newsexpressngr.com/news/detail.php?news...
Obviously not slow enough, as this occurred during a parking maneuver.

So how slow do you have to go in order to eliminate serious injuries?
http://www.newsexpressngr.com/news/detail.php?news...
Obviously not slow enough, as this occurred during a parking maneuver.

[Phatboy317]

vonhosen said:

It was rubbish when it was covered on the other threads as well then.

No-one was saying you left home at the same time & would be there at 40mph or 30mph when the object appeared in front of you. In the comparison it's that you were at that point doing one of those different speeds when the object appeared & the resulting differences in outcome as a result of that speed in those circumstances.

Your comparison makes the assumption that the object is always going to appear at some fixed distance ahead of you, which is complete nonsense. It could be 100 metres, it could be 10 metres, it could be anything. And it does not, and cannot, have any connection to the speed you happen to be doing at the time.

The only thing you can say is that if an object appears x metres ahead of you when you're doing a particular speed, and, on another occasion, (or in some parallel universe) an object appears the same x metres ahead of you when you're doing a different speed, then you're more likely to hit the object at the higher speed.
But, given that each occasion is only going to happen a few times at the most in the average driver's lifetime, if at all, the same distance coming up twice is hugely improbable.

The only valid comparison which can be made is to compare the size of the time window at different speeds, during which passing a certain point will result in you being within the stopping distance of the object at the time it enters the road ahead of you.
But even that will only give a statistical comparison - it still cannot be used to compare individual events.

[vonhosen]

Phatboy317 said:

vonhosen said:

It was rubbish when it was covered on the other threads as well then.

No-one was saying you left home at the same time & would be there at 40mph or 30mph when the object appeared in front of you. In the comparison it's that you were at that point doing one of those different speeds when the object appeared & the resulting differences in outcome as a result of that speed in those circumstances.

Your comparison makes the assumption that the object is always going to appear at some fixed distance ahead of you, which is complete nonsense. It could be 100 metres, it could be 10 metres, it could be anything. And it does not, and cannot, have any connection to the speed you happen to be doing at the time.

The only thing you can say is that if an object appears x metres ahead of you when you're doing a particular speed, and, on another occasion, (or in some parallel universe) an object appears the same x metres ahead of you when you're doing a different speed, then you're more likely to hit the object at the higher speed.
But, given that each occasion is only going to happen a few times at the most in the average driver's lifetime, if at all, the same distance coming up twice is hugely improbable.

The only valid comparison which can be made is to compare the size of the time window at different speeds, during which passing a certain point will result in you being within the stopping distance of the object at the time it enters the road ahead of you.
But even that will only give a statistical comparison - it still cannot be used to compare individual events.

No not always at distance x, just in that particular case. Another time it could be 2 metres further ahead & still the 40mph vehicle will strike it & the 30mph vehicle won't, it's just the 40mph will strike it at a slighter lower speed than in this case. 2metres closer & both will strike it, only the 30mph vehicle at will be going a lot slower than the 40mph vehicle when it does (which will be far more than their initial speed differential).

Edited by vonhosen on Monday 20th October 19:03

[Phatboy317]

OTBC said:

http://www.bmj.com/content/339/bmj.b4469

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%).

End quote. That's why Southwark, ISlington and now Camden are introducing Home Zones, they're proven to work, they save lives, and they do so by reducing drivers' speeds.

That study covers the period ending in 2006, and the sample sizes are statistically tiny.

Since then, 20mph limits have been implemented on a large scale, in many cases city-wide, in places like Bristol and Portsmouth, so we should have large amounts of data for the most recent eight years.

So where are the new studies? If they have been so effective then surely they should be shouting the results from the rooftops, shouldn't they?

[Phatboy317]

vonhosen said:

No not always at distance x, just in that particular case. Another time it could be 2 metres further ahead & still the 40mph vehicle will strike it & the 30mph vehicle won't, it's just the 40mph will strike it at a slighter lower speed than in this case. 2metres closer & both will strike it, only the 30mph vehicle at will be going a lot slower than the 40mph vehicle when it does (far more than their initial speed differential).

You're just not getting it, and I don't know how to make it any clearer.

All I can suggest is, if you know how to, that you try to create a computer simulation to help you visualise what happens.

[johnao]

singlecoil said:

If the accidents are caused by factors other than speed then getting everyone to slow down is an excellent idea because it will reduce the severity of those accidents.

Where are you going with this? Getting everyone to walk everywhere would be a good way of... getting everyone to slow down, [and it would be] an excellent idea because it will reduce the severity of those accidents.

[singlecoil]

johnao said:

singlecoil said:

If the accidents are caused by factors other than speed then getting everyone to slow down is an excellent idea because it will reduce the severity of those accidents.

Where are you going with this? Getting everyone to walk everywhere would be a good way of... getting everyone to slow down, [and it would be] an excellent idea because it will reduce the severity of those accidents.

It's pointless removing one sentence from a conversation and asking for an explanation of it. Read it in context and hopefully you will see what I am getting at.

[Phatboy317]

OTBC said:

Really, this is basic human physics, the human body can withstand running into a tree at top speed, sub twenty mph for all. Above that speed the risk of injury or death increases exponentially. Basic human biology, or physics, call it what you like but if you're still in doubt I can drive a metal box that weights two tones into you at fifteen mph then thirty mph and you can tell us what hurts more. Deal?

Then you wouldn't mind illustrating your point by making a video of yourself running at full tilt into a tree?
Or a wall?
Or into the front of a parked car?

Thought not...

[Phatboy317]

singlecoil said:

Nonsense. If the accidents are caused by factors other than speed then getting everyone to slow down is an excellent idea because it will reduce the severity of those accidents.

Because cars have brakes, there's only a very loose connection between travelling speed and severity of accidents.

For instance, the number of pedestrians killed amounts to a figure in the order of 1% of total number of pedestrian casualties, whereas we are told that the physics suggest that the figure should be around 2 orders of magnitude higher.

You're quite welcome to examine the STATS19 data yourself if you don't believe me.

And if the false sense of safety engendered by lower speed limits leads to more accidents due to people taking less care, then they can actually be counter-productive.

Edited by Phatboy317 on Monday 20th October 21:37

[singlecoil]

Phatboy317 said:

singlecoil said:

Nonsense. If the accidents are caused by factors other than speed then getting everyone to slow down is an excellent idea because it will reduce the severity of those accidents.

Because cars have brakes, there's only a very loose connection between travelling speed and severity of accidents.

For instance, the number of pedestrians killed amounts to a figure in the order of 1% of total number of pedestrian casualties, whereas we are told that the physics suggest that the figure should be around 2 orders of magnitude higher.

You're quite welcome to examine the STATS19 data yourself if you don't believe me.

Edited by Phatboy317 on Monday 20th October 21:31

You would have a better chance of my believing you if you didn't come across like a one man single interest pressure group (not that you are going to apply very much pressure with arguments of that quality).

[Phatboy317]

singlecoil said:

You would have a better chance of my believing you if you didn't come across like a one man single interest pressure group (not that you are going to apply very much pressure with arguments of that quality).

Personally, I don't care what you believe.

I only care about the truth.

So if you think I'm wrong, prove it.

[OTBC]

Phatboy317 said:

That study covers the period ending in 2006, and the sample sizes are statistically tiny.

Since then, 20mph limits have been implemented on a large scale, in many cases city-wide, in places like Bristol and Portsmouth, so we should have large amounts of data for the most recent eight years.

So where are the new studies? If they have been so effective then surely they should be shouting the results from the rooftops, shouldn't they?

What size sample do you consider statistically invalid? That's a peer-reviewed piece of research, university departments don't lend their name to any old papers.

[OTBC]

Phatboy317 said:

Then you wouldn't mind illustrating your point by making a video of yourself running at full tilt into a tree?
Or a wall?
Or into the front of a parked car?

Thought not...

That would be an excellent experiment if I wished to establish a relationship between speed on collision and injuries inflicted. Are you sure that's the experiment you mean?

Lower speeds means that the severity of injuries is reduced. There is zero evidence to the contrary, that's why the only statistic quoted by the speedophiles is the discredited nonsense from the ABD.