Stop Headway

This sub-forum all discussions about this "lively" subject. All topics that are substantially about helmets will be moved here, if not placed here correctly in the first place.
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bovlomov
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Re: Stop Headway

Postby bovlomov » 23 Dec 2010, 10:21am

irc wrote:Did anyone doubt this?

Judging by the column inches and airtime given to the subject, yes.

MikeL
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Re: Stop Headway

Postby MikeL » 23 Dec 2010, 10:55am

We do not know * where* these bike/ped collisions occurred. I suspect most or all of them were on the pavement. If I am correct, then those of us who always ride on the road represent a risk to the public of near enough to zero to make no practical difference.

The pedestrian fatality rate *may* be an underestimate, depending on how you define causality. For an old person, suffering a broken neck of femur after being knocked down by a bike (easily plausible) could well set in train a sequence of events which leads to chronic debility and eventually death even if many months later. Would this be counted? It would be a source of bias, since injuries caused by motor traffic would be more likely to cause early death because of the greater trauma.

SilverBadge
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Re: Stop Headway

Postby SilverBadge » 23 Dec 2010, 11:08am

MikeL wrote:We do not know * where* these bike/ped collisions occurred. I suspect most or all of them were on the pavement. If I am correct, then those of us who always ride on the road represent a risk to the public of near enough to zero to make no practical difference.
IIRC you are wrong - more than half are on the carriageway, not sure what the blame apportionment is. Whilst it is a "constipated, Holmes?" to point out that that it's far easer to kill a pedestrian with a car, even on the pavement, perception is otherwise.

The pedestrian fatality rate *may* be an underestimate, depending on how you define causality. For an old person, suffering a broken neck of femur after being knocked down by a bike (easily plausible) could well set in train a sequence of events which leads to chronic debility and eventually death even if many months later. Would this be counted? It would be a source of bias, since injuries caused by motor traffic would be more likely to cause early death because of the greater trauma.
There is a standard definition of death "cause" which is time-related, probably different for murder/manslaughter vs RTA (sic). A greater proportion of car-derived fatalities are likely to be instant/quick but the same threshold injury, be it car or bicycle induced, could fall foul of this.

MikeL
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Re: Stop Headway

Postby MikeL » 23 Dec 2010, 11:51am

SilverBadge wrote: IIRC you are wrong - more than half are on the carriageway, not sure what the blame apportionment is. Whilst it is a "constipated, Holmes?" to point out that that it's far easer to kill a pedestrian with a car, even on the pavement, perception is otherwise.


Oh the benefits of fact free argumentation! Reasoning that ped fatalities are rare enough to make the news I did a google search. In the first page or so there were three fatalities reported in 2007.

Nick Bancroft - Road
Rhiannon Bennett - disputed in court, probably road
Gary Green - Pavement

Not scientific, but casts severe doubt on my hypothesis. You win :)

As a side-note Ms Bennetts father complained bitterly about the inadequacy of the £2500(!) fine. While not necessarily disagreeing with him, this is about 10x the typical fine when a motorist kills someone (whether on bike or foot).

I still wonder about underrecording of delayed deaths as a consequence of 'minor' injuries.

Mike

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Re: Stop Headway

Postby snibgo » 23 Dec 2010, 6:16pm

I think the cutoff for "killed as a result of accident" is one month.

Here is the same analysis for serious injuries. The larger numbers will vary less between years. I have ordered them with safest at the top and most dangerous at the bottom.

(Vehicle type: billion vehicles miles [table 1b]; serious pedestrian injuries in single-vehicle accidents [table 22]; calculated serious pedestrian injuries per billion vehicles miles)

Light good vehicles: 41; 247; 6.02
Heavy good vehicles: 16; 109; 6.81
All motor vehicles: 313; 5091; 16.27
Cars and taxis: 249; 4100; 16.47
Pedal cycles: 3.1; 73; 23.55
Motorcycles: 3.2; 193; 60.31
Buses and coaches: 3.2; 293; 91.56

Very bad news for those of us who considered cycling to be safe for pedestrians: it isn't.

A cycle is more dangerous (EDIT: per mile) to a pedestrian than an LGV, HGV or car. It is worse than the average motor vehicle. In absolute numbers, cycles are very safe for pedestrians, but this is only because of the low number of miles cycled.

I suspect that most cycle-versus-pedestrian collisions are on pavements, although the single fatality in 2009 wasn't.

kwackers
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Re: Stop Headway

Postby kwackers » 23 Dec 2010, 6:34pm

snibgo wrote:A cycle is more dangerous (EDIT: per mile) to a pedestrian than an LGV, HGV or car. It is worse than the average motor vehicle. In absolute numbers, cycles are very safe for pedestrians, but this is only because of the low number of miles cycled.

I suspect that most cycle-versus-pedestrian collisions are on pavements, although the single fatality in 2009 wasn't.

I'm curious as to why the figure for motorcycles is so high.
Is it because they filter? If so is this possibly one of the reasons bicycles do badly?
(I'm feeling there's a connection in there somewhere...)

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meic
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Re: Stop Headway

Postby meic » 23 Dec 2010, 7:36pm

The figures would probably be a lot different if there was a cyclist equivalent of motorways, where cyclists could do millions of miles safe from any chance of hitting pedestrians.

Also the figures are probably higher for cycles and motorcycles because pedestrians ( the same people as motorists but out of their cars) are not expecting them and dont notice them.
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snibgo
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Re: Stop Headway

Postby snibgo » 23 Dec 2010, 8:24pm

meic wrote:The figures would probably be a lot different if there was a cyclist equivalent of motorways, where cyclists could do millions of miles safe from any chance of hitting pedestrians.

Agreed. And if pedestrians, cycles and motor vehicles were all entirely segregated from each other, they would all be entirely safe from each other.


In 2009 there were 30 motorway injuries in accidents between pedestrians and single vehicles. Of these, 9 were serious and a further 8 were fatal.

I can redo the analysis, ignoring the miles driven on motorways. (I should also ignore the 9 serious injuries caused to pedestrians on motorways by each vehicle type, but DfT doesn't seem to provide this detail.)

(Vehicle type: total billion vehicle miles minus billion vehicle miles on motorways [table 1b]; serious pedestrian injuries in single-vehicle accidents [table 22]; calculated serious pedestrian injuries per billion vehicles miles that aren't on motorways)

Light good vehicles: 41 - 7.6 = 33.4; 247; 7.40
Heavy good vehicles: 16 - 7.0 = 9.0; 109; 12.11
All motor vehicles: 313 - 62 = 251; 5091; 20.28
Cars and taxis: 249 - 47 = 202; 4100; 20.30
Pedal cycles: 3.1 - 0.0 = 3.1; 73; 23.55
Motorcycles: 3.2 - 0.3 = 2.9; 193; 66.55
Buses and coaches: 3.2 - 0.3; 293; 101.03

As expected, this shows increased injury rates per mile for all groups except cycles, but not by enough to change the ordering.

For me, the take-home message is that while cyclists very rarely cause deaths, they (we) DO cause serious injuries. We might counter this by the number of deaths caused by road pollution, but it is still a worrying message. Take care of pedestrians, folks!

Here's an anecdote: I was buying a hot-dog the other day while holding the bike with one hand. The bike slipped away from me, drove in reverse around me and fell over, coming very close to clouting the person in front of me in the queue.

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7_lives_left
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Re: Stop Headway

Postby 7_lives_left » 23 Dec 2010, 8:49pm

meic wrote:Also the figures are probably higher for cycles and motorcycles because pedestrians ( the same people as motorists but out of their cars) are not expecting them and dont notice them.

(My emphasis). It's not just motorists. I managed to walk out in front of a cyclist when visiting Oxford. Fortunately he didn't hit me but I did force him to swerve and stop. My fault entirely. I stepped off the footway to pass a pair of pedestrians walking towards me. The cyclist was approaching me from behind. It was a minor road with through traffic for bikes only.

As I am lazy I very rarely walk anywhere but I am not familiar with Oxford so I find it easier to park the bike and walk. I'm just not used to the all the bicycle traffic.

snibgo
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Re: Stop Headway

Postby snibgo » 23 Dec 2010, 9:00pm

Anyone who is still awake and is (like me) searching for escape clauses from these uncomfortable statistics might ask: "Ah, but these are for single-vehicle collisions. Surely some pedestrians are seriously injured in multiple-vehicle collisions, swinging blame more towards motor vehicles?"

The answer is: yes, but not enough to make much difference. Table 23a shows that 4449 pedestrians were seriously injured in single-vehicle accidents, and only 304 in multiple-vehicle accidents.

I pulled all the statistics from http://www.dft.gov.uk/pgr/statistics/da ... /rrcgb2009

Feel free to check my work. I hope I've made a mistake.

Mike Sales
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Re: Stop Headway

Postby Mike Sales » 23 Dec 2010, 9:23pm

Accident rate should be reckoned against exposure.
A much higher proportion of cycle miles than car miles are done in towns. I have no figures and I have a suspicion they are not collected, though I may be wrong. We should not use the raw figures for miles travelled by mode. Also there are few pedestrians where most car miles are done, on main roads outside built up areas.
Unfortunately bikes do many more miles on the pavement than cars, so the pavement death rate ( cars killing many more than bikes ) reflects the real lethality, in spite of the exposure to bike collisions being so much higher.
On roads in town, as "7 lives left" writes, pedestrians are looking out for cars, but not bikes. Risk compensation here. Whether the cyclist or driver is travelling carefully and in accordance with the H.C. or not, pedestrians take much more care in avoiding being hit by a car.
In the end risk compensation implies that people will take the amount of care that the risk demands. Bikes inflict little risk, pedestrians pay more attention to the major risk, so that they avoid the hugely greater danger from cars more effectively.
(I am using "cars" to include all motor vehicles.)

Steady rider
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Re: Stop Headway

Postby Steady rider » 23 Dec 2010, 9:49pm

The figures for risk could be interesting per hour of travel,

eg assume cyclists average 10 mph, motorcyclists 30mph, others 25 mph.

Light good vehicles: 41 - 7.6 = 33.4; 247; 7.40
Heavy good vehicles: 16 - 7.0 = 9.0; 109; 12.11
All motor vehicles: 313 - 62 = 251; 5091; 20.28
Cars and taxis: 249 - 47 = 202; 4100; 20.30
Pedal cycles: 3.1 - 0.0 = 3.1; 73; 23.55
Motorcycles: 3.2 - 0.3 = 2.9; 193; 66.55
Buses and coaches: 3.2 - 0.3; 293; 101.03


Buses and coaches: 3.2 - 0.3; 293; 101.03
2.9 / 25 = 0.116, 293 / 0.116 = 2525 (2.5 per million hours)

Motorcycles: 3.2 - 0.3 = 2.9; 193; 66.55
2.9 / 30 = 0.1, 193/0.1 = 1930 (1.9 per million hrs)

All motor vehicles: 313 - 62 = 251; 5091; 20.28,
251 /25 = 10 billion hrs, 5091/10 = 509 (0.5 per million)

Pedal cycles: 3.1 - 0.0 = 3.1; 73; 23.55
3.1/ 10 = 0.31, 73 / 0.31 = 235 (0.235 per milion hrs)


hoping I have these figues right.
assuming these estimates are somewhere near, cyclists could pose the lowest risk, assuming also the 3.1 billion miles is about right, would it include children pedalling in parks for example. The risk to pedestrians by cyclists could also be considered against the risk per hour for the cyclist on the road. The risk from cyclists could also be considered on a pollution basis and fatality calc per hour may also be worthwhile.
fatality data
Pedal cycles: 3.1; 1; 0.32
Motorcycles: 3.2; 8; 2.50
Cars and taxis: 249; 291; 1.17
Buses and coaches: 3.2; 37; 11.56
Light good vehicles: 41; 16; 0.39
Heavy good vehicles: 16; 58; 3.62
All motor vehicles: 313; 420; 1.34


All motor vehicles 313/25 = 12.5, 420/12.5 = 33.6 per billion hrs
Motorcycles: 3.2/30 = 0.1, 8/0.1 = 80
Pedal cycles: 3.1/10 = 0.31, 1/0.31 = 3.2

Cyclists should be very careful when near to pedestrians but they are not a major problem.
Last edited by Steady rider on 23 Dec 2010, 10:56pm, edited 1 time in total.

belgiangoth
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Re: Stop Headway

Postby belgiangoth » 23 Dec 2010, 10:47pm

It would be interesting to see whether cycling numbers increasing correlate to more or less cycle-ped accidents (in the same way as they hopefully reduce cycle-motorist accidents).
Maybe we should find out how the UK compares with the mainland for these stats?
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snibgo
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Re: Stop Headway

Postby snibgo » 24 Dec 2010, 12:05am

@Steady Rider: I agree with your calculations and conclusions. They show that, provided we accept your speed estimates, a cyclist is less likely per hour of travelling to injure a pedestrian than a car is. Or any other group apart from LGVs.

I agree with Mike Sales that a better measure of risk is by exposure of pedestrians to each vehicle type.

For example, if I walk around town on a pavement am I more likely to be killed by a car or bike? Answer: a car, even though, as Mike points out, moving bikes on pavements are far more common than cars.

But am I more likely to be seriously injured by a car or bike? I'm not sure if the statistics provide the answer. We would need to know how many of those 73 serious injuries of pedestrians with cycles occur on pavements (which is probably recorded), as well as how much cycling is done on pavements (which probably isn't).

However, the CTC says that in 2001-5, on London footpath or verge, 12 pedestrians suffered serious injury from collision with cycle, and 387 from collision with motor vehicle. (http://www.ctc.org.uk/resources/Campaig ... nt_brf.pdf, citing "unpublished data from TfL Road Safety Division, Department for Transport.")

And, yes, it would be interesting to compare the numbers with mainland Europe (especially the Netherlands).

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Cunobelin
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Re: Stop Headway

Postby Cunobelin » 24 Dec 2010, 6:22am

meic wrote:The figures would probably be a lot different if there was a cyclist equivalent of motorways, where cyclists could do millions of miles safe from any chance of hitting pedestrians.

Also the figures are probably higher for cycles and motorcycles because pedestrians ( the same people as motorists but out of their cars) are not expecting them and dont notice them.


Noise has a lot to do with it

When electric vans were becoming used by some of the larger City Councils the accident rate went up even for their better drivers.

The suggestion is that pedestrians were listening for engines and not hearing them assuming that they were clear to step out ... into the path of the silent electric vehicle

Some vehicles now have noisemakers for this reason.

Are cycles also too quiet?