Motorcycle accident myths - A public presentation on the facts

[Berries]

Sorry but I'm a bit unclear on exactly what your 1:14 ratio refers to.Is it injury:non-injury accidents?

They reckon that only one in 14 non injury crashes gets reported and makes it on to the database, which is a best guess.

Here’s those numbers anyway. First figure is number of all reported crashes involving motorbikes across NZ (including non injury). Second figure is the number of them that were multi vehicle, third figure is the number that were single vehicle. Total crashes includes bike vs cyclist and bike vs ped crashes which explains the difference of 115 if you add them all up. Note that mopeds are often incorrectly coded as motorbikes so may feature in these numbers and go a little way to explain the increases.

2005 1064 753 293 (27%)
2006 1088 764 307 (28%)
2007 1347 911 408 (30%)
2008 1507 998 477 (32%)
2009 1442 961 461 (32%)

I do quite a bit of crash analysis at work which is why I am interested in this presentation, to get the thread back on topic.

[Bass]

They reckon that only one in 14 non injury crashes gets reported and makes it on to the database, which is a best guess.

Whoa!
So that means what? It doesn't actually allow us to calculate the total number of accidents, does it? (Thanks BTW).

Worse, that the sample we have ,(the reported events), is not a random one and so may be completely unrepresentative of the total event population?

Indulging in a bit of surmise for a second, it could for example be argued that collision with another vehicle is more likely to cause injury than just coming off and so the unreported accidents are more likely to be single vehicle events?

That has to make it really difficult to accurately say anything about motorcycle accidents overall.

I wonder how Prof Lamb got around that one.

[p.dath]

“The largest single determinant of accidents is visibility issues affecting drivers of other vehicles involved in motorcycle accidents"

The largest SINGLE determinant. I reckon it is true. What I can not understand is why people ride around wearing black helmets, black clothes and bikes that are painted in dull colors. Are they just plain stupid or is something else driving their behavior?

The tricky bit is Maki, when they have looked at the accident rates between high-viz users and non-high viz users in accidents where the cage claims not to have seen them - the rates are about the same to within 1%.

It seems that when a cage does not see a motorcycle, they don't see them no matter what they are wearing.

[Bass]

It seems that when a cage does not see a motorcycle, they don't see them no matter what they are wearing.

I'm interested.
Do you have a link to an appropriate study?

[Ixion]

They reckon that only one in 14 non injury crashes gets reported and makes it on to the database, which is a best guess.

I'd suspect (without any evidence) that bike crashes (injury and non injury) are reported more often. If a bike goes down, someone always calls the cops. And usually an ambulance.

It seems that when a cage does not see a motorcycle, they don't see them no matter what they are wearing.

I don't have any evidence for this, either, but personal experience suggests it is pretty much so. I ride a variety of bikes. And I vary what I wear. Sometimes it's a black bike, black leather and black helmet. Sometimes a big all white bike, hi-viz jacket (not just a vest) , and white helmet. And all combinations in between, including variously coloured bikes. With and without headlights on. It doesn't really seem to make much difference.

Once, some years ago, my perception was that the hi-viz and headlamp combo did make a signifcant differnce. But it seems to have lost its edge nowadays (I suspect because hi-viz and headlamps are both so common now, it no longer has the WTF is that factor).

[Berries]

So that means what? It doesn't actually allow us to calculate the total number of accidents, does it? (Thanks BTW).

No. We will never know the true number of crashes of any type. If I dropped my bike on a corner, completely my own fault, would I bother reporting it ? If I was going to make an insurance claim then possibly, otherwise highly unlikely.

Indulging in a bit of surmise for a second, it could for example be argued that collision with another vehicle is more likely to cause injury than just coming off and so the unreported accidents are more likely to be single vehicle events?

Possibly, and to refute that argument the only data available is the same data where we know so much is missing. Catch 22. Data like the ‘reported’ single bike stats show a much higher severity rate than multi vehicles crashes (47% of injury crashes were fatal or serious compared to 37%) or that only 11% of reported bike crashes were non injury compared to 31% of multi vehicle crashes. May not be totally accurate, but does paint a picture.

You could also argue that a two vehicle incident is more likely to get reported because one party will want to be claiming off the other, or that because they are more likely to be in an urban area (72% of multis were urban compared to only 36% of singles) they are more likely to get Police attendance.

That has to make it really difficult to accurately say anything about motorcycle accidents overall. I wonder how Prof Lamb got around that one.

I don’t think it is a case of getting around it, you can only talk accurately about the information at hand and if we don’t report crashes we are involved in then we can’t complain that the full information isn’t available. What will make the presentation interesting is that the Prof has actually looked at the crash reports which will take it beyond the usual simplistic road safety messages we get hammered with.

[Bass]

No. We will never know the true number of crashes of any type. If I dropped my bike on a corner, completely my own fault, would I bother reporting it ? If I was going to make an insurance claim then possibly, otherwise highly unlikely.


only 11% of reported bike crashes were non injury .

You have thrown some new information in there.
Therefore, if we know the number of reported crashes, that 11% of them were non-injury and that only 1in 14 (guesstimate) non-injury are reported, we can calculate an estimated total.
e.g. 2009 1442 reported
11% non injury = 159 and 1283 injury
If 149 is 1/14 of total non-injury then total is 2086
Total accidents is then 1283 + 2086 = 3369
It's only a rough estimate, I know, but it's the number I was trying to get some sort of handle on. Thanks again.

[Katman]

Total accidents is then 1283 + 2086 = 3369
It's only a rough estimate, I know, but it's the number I was trying to get some sort of handle on. Thanks again.

We're not very good at this motorcycling lark, are we?

[Maha]

Radio advert.....

'70% of all motorcycle accident involve another vehicle and 33% (30 something anyway?) of those accidents are not the motorcycles fault'.
So I take it that 30% of motorcycle accidents dont involve another vehicle? Rider error?
What then, is the total percentage (going on the figures above) of motorcycle accidents, that are the other vehicles fault?

[Katman]

33% of 70 = 23.1

Therefore (according to the figures you've given) 46.9% of motorcycle accidents are the fault of another vehicle.

[Maha]

33% of 70 = 23.1

Therefore (according to the figures you've given) 46.9% of motorcycle accidents are the fault of the other vehicle.

So, more than half of all bike accidents are (going by those figures) the motorcycles fault?
Is your figure correect Steve? 46.9%?

I would have thought it would be less than that?
Isn't it 23.1%?
Because its out of 100 not 70....I could be wrong.

[Katman]

Because its out of 100 not 70....I could be wrong.

The 33% figure is for the multi-vehicle accidents only - not all motorcycle accidents.

[Sentox]

FML. See post #60.

[Maha]

His math is correct.

Still, following the language of the statement strictly, you can say that 46.9% of accidents involving a motorcycle are not the fault of another vehicle. You can't state categorically that the 53.1% of accidents are the fault of the rider though... invisible road hazards, animals entering the road, etc.

So the Radio add could be misleading in the way it words the figures?

[Sentox]

So the Radio add could be misleading in the way it words the figures?

Damn, you got in before my edit I cocked it up a little first time around.

A little bit. It's fair to say that a good portion of motorcycle accidents are the rider's fault, but you can't extrapolate the exact figure from that statement without more details.

Edit: ARGH BRAIN FAIL. Re-reading the original statement: 70% of accidents involve other vehicles. 33% of those are not the rider's fault; therefore, they are implicitly another vehicle's fault. 23.1% of all motorcycle accidents are the fault of another vehicle.

Edit #2: Well, to be totally pedantic, 23.1% of accidents involve another vehicle and were not the rider's fault. Depends how they assign blame and deal with factors like mechanical breakdown, invisible hazards like diesel, etc.