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#31
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UK cyclists kill or maim two people a week
On 19/10/17 17:51, Peter Parry wrote:
On Wed, 18 Oct 2017 09:37:51 +0100, TMS320 wrote: On 17/10/17 14:49, Peter Parry wrote: On Mon, 16 Oct 2017 22:15:16 +0100, TMS320 wrote: On 15/10/17 18:35, Peter Parry wrote: On Fri, 13 Oct 2017 00:28:39 +0100, TMS320 You have to have a common base to allow for the detection of trends. Looking for impacts per pedestrian mile or impacts per pushbike mile is going to produce the same result.Why they chose the measurement they have I do not know - but it seems to be used by many road transport investigators worldwide. The French look at it by population... As I said, their figures show no connection between casualties and vehicle distance, pedestrian or occupant. A vehicle/bike/pedestrian is exposed to the risk of an accident whenever it is on the road. It would be surprising if the likelihood of an event turned out to be unrelated to the exposure to the risk be that in terms of miles traveled or hours driving/walking etc. Yes, for vehicle occupant casualty against vehicle distance or for pedestrian casualty against distance walked. Not for pedestrian casualty against vehicle distance! This is what I take issue to. You can certainly use the overall measure of accidents per million inhabitants per year to see if large scale policies are having an overall effect and you could use the same measure for groups within the whole - what you cannot do is use the measure of accidents per million inhabitants to compare the relative probability of an accident across multiple groups. The French appear to use accidents/million population for overall figures and accidents/million km for comparative purposes (for example comparing accidents attributed to foreign drivers against locals). They also use accidents per hour when looking at relative risks. In the recent documents I have I see no figure for pedestrian casualties per vehicle distance. Perhaps I have missed it? They used to list pedestrian casualties by department but unfortunately it seems they no longer do so and just lump all road users together. They also lament the poor quality of data collection "Accidents with pedal cyclists who were hospitalised are very under estimated in the national register of accidents particularly as the police and gendarmerie are not always called to these accidents especially if no motorist is involved." Perhaps, but we're not discussing pedal cyclist versus distance cycled. The death to injury ratio (RAS30018 Reported casualties sheet), removing the vehicle-distance element, is the only thing that provides us with an indication of the severity of non-fatal injuries in a collision, The severity of injury data for more serious injuries at is available in hospital admission data and has certainly been included is some studies. if a smaller proportion of injuries convert to death, there must be fewer life threatening injuries in the mix. Which has no relationship with causation. We're not discussing causation either. We are discussing the figures. You emphasise accuracy of injury reporting but make no mention of accuracy of distance reporting. All of the data collection concerning cycling accidents is inaccurate. The main impact is seen in the often poor design of measures meant to reduce pushbike casualties. There measures are more likely to be political and nothing to do with data. Politicians are not noted for their intelligence and their general mantra is "Don't just stand there - do something" where "something" can bear no relationship to the problem. They tend to be overly influenced by shouty lobby groups (who are also rarely interested in the truth, their mind is made up and they don't want to be confused by facts). The civil servants who do make up the briefing papers would dearly like better facts as they generally do like getting the right answer. Indeed. |
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#32
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UK cyclists kill or maim two people a week
On 10/10/2017 13:09, TMS320 wrote:
On 09/10/17 00:12, TMS320 wrote: On 08/10/17 08:52, MrCheerful wrote: We were told that their low inertia and rotating couples couldn't hurt a fly, *We* have not been told this. http://www.express.co.uk/news/uk/863...ans-every-week ...compared to the 10 a week killed and 100 a week injured by drivers. On Jeremy Vine yesterday (I can't a weblink to the story), Never mind. You'll probably find a job soon, one hopes. a case of driver being cleared of killing someone on a zebra crossing helps build a case of there being one law for drivers and another for cyclists. Actually, the figures above are interesting. We are told that cycle journeys represent 2% of road journeys (I can't be bothered to verify). Even if it were true (as unlikely as it sounds - just think of how few daily cyclists live in *your* street, wherever it may be), it would certainly not be true on a distance travelled basis. In the last three weeks, I've driven just under 5,000 miles. Can anyone claim anywhere near that distance on a bike in the same sort of time-frame? The figures show that injuries involving bicycles are about 2% (*) of those involving motor vehicles. So a lot more bicycle accidents per mile travelled. But 6.8% of the injuries involving motor vehicles lead to death, whereas only 1.8% of the injuries involving a bicycle do so. Which also means that out of the whole spectrum of non-fatal injuries, those from a bicycle must be much less severe. So yes, it demonstrates that bicycles are considerably less dangerous. Less dangerous? Or less deadly? Just because a badly-ridden bike is more likely to break a pedestrian's collarbone rather than their spine, that is not to say that being hit by a bike is not dangerous. (*) Direct correlation or coincidence? Impossible to know because it is likely that a greater proportion of vehicle journeys are through non-dense urban areas or that pedestrians stay out of the way of areas with heavy traffic. Why does that matter? |
#33
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UK cyclists kill or maim two people a week
On 11/10/2017 10:20, TMS320 wrote:
On 11/10/17 09:35, Peter Parry wrote: On Tue, 10 Oct 2017 12:06:02 -0700 (PDT), Simon Jester Do these figure take into account that the majority of car miles are on trunk roads where there are few, if any, pedestrians? Whilst bicycles spend most of their time in urban environments. If not then they are worthless. They do. On urban roads Pushbikes seriously injure 26 pedestrians per billion km and kill 0.5, cars seriously injure 10 and kill 0.7. So you love to push this. Irrespective of car bike/figures, explain why you think pedestrian casualties per vehicle-distance is meaningful. Try to bear in mind my earlier point about figures from France that show no connection. Exposure to risk / danger / hazard? You can't fall down the stairs in a bungalow and you can't have an accident on your bike whilst you're not on it. You are on it longer the more miles you do (on it). |
#34
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UK cyclists kill or maim two people a week
On 14/10/2017 20:43, TMS320 wrote:
On 14/10/17 15:08, Simon Jester wrote: On Friday, October 13, 2017 at 2:04:43 PM UTC+1, Nick wrote: On 13/10/2017 00:28, TMS320 wrote: On 12/10/17 22:11, Peter Parry wrote: On Thu, 12 Oct 2017 01:07:40 +0100, TMS320 wrote: On 11/10/17 12:28, Peter Parry wrote: On Wed, 11 Oct 2017 10:20:28 +0100, TMS320 wrote: On 11/10/17 09:35, Peter Parry wrote: On Tue, 10 Oct 2017 12:06:02 -0700 (PDT), Simon Jester Do these figure take into account that the majority of car miles are on trunk roads where there are few, if any, pedestrians? Whilst bicycles spend most of their time in urban environments. If not then they are worthless. They do. On urban roads Pushbikes seriously injure 26 pedestrians per billion km and kill 0.5, cars seriously injure 10 and kill 0.7. So you love to push this. "Push"?Â* One mention of DfT statistics is pushing them? Yes. You have brought this up several times before. It is obvious you think it is meaningful. It is clearly meaningful as it is the data used by the government to make decisions. I asked you why you think pedestrian casualties per vehicle-distance is meaningful. Don't evade the question. Of course it is. That doesn't answer the question. You won't get an answer. He won't even attempt an answer because he knows he isn't clever enough. FWIW the effect you are talking about with respect urban/non urban trips is called Simpson's Paradox. https://en.wikipedia.org/wiki/Simpson%27s_paradox So what metric should we use? Passanger miles don't count because there is only one driver per vehicle. Passenger miles isn't too bad - even if there is a passenger variation from 1 to 5; at least they're actually inside the vehicles that are doing the miles. (I expect Simpson's paradox would find a strange result between 1 occupant, 5 occupants and average occupancy - whatever that average is.) I just canot fathom out why there is supposed to be a link between pedestrians and vehicle miles. Pedestrians are, in terms of vehicles, objects in the landscape. Like trees or brick walls but less hard and liable to move about. The more time you spend cycling within that landscape, and the greater the density of pedestrians (humans) within it, the greater the likelihood of a collision with a pedestrian. But perhaps if analysing the frequency of cyclists crashing into brick walls, you would refuse to take into account the number of brick walls and the time spent cycling with a brick wall in the vicinity? |
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