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This is worth doing, but as written it is a bit confusing. If I follow you, the problem is that you don't have an estimate of the number of miles of cycling or driving. If you did, this is much simpler. If the ratio of miles driven to miles cycled is greater than 62, then cyclists collide with pedestrians more per mile than do drivers. Given the large number of cyclists on sidewalks compared to drivers on sidewalks, it should not be that surprising.

Of course, perhaps cyclists travel less, and so it might be interesting to compare accidents per hour.

It's hard to tell what we are actually getting with these exposure estimates. Maybe we need to better define what we are trying to measure

Yeah, you are jumping all over the place with unassociated stats, spanning completely different periods.

Here is the core of the issue, per your link to DDOT above:

"Over the 1997-1999 time period, bicycle collisions account for approximately 2 percent of all traffic collisions". Bicycles are (as cycle blogs keep trumpeting) now responsible for a full 2% of all trips taken in the District.

There, an apples to apples comparison that isn't rocket science, that also shows that yes, bikes are just as statistically responsible for their "share" of accidents.

Actually, the argument could be made that since these numbers are ~11 years old, and the number of total trips by bikes was less then than it is now <2%, that bikes were statistically more responsible for accidents than vehicles were.

Nookie, since your assertion - to me - is so obviously flawed, and I'm pretty sure I've already shown you how on another thread, and since I feel you're intellectually dishonest, I'm not going to bother showing you the flaws unless someone else replies that they find your argument convincing.

Jim, this is confusing - I'm sorry - and I tried really hard to not make it so. I have the number of miles, but not hours. But either way cyclists are in fewer crashes with pedestrians. Another way to think of this is that, on average a cyclist would have to ride 1.28 Million miles to be in a reported crash with a pedestrian. A driver would only need to go 202 hundred thousand miles to be in a reported crash with a pedestrians. If you go with hours on the road - a better metric in my opinion - the gap becomes even larger. That's the point.

Thanks David. So if I am following you, there is one crash per 1.28 million cycling miles, because cyclists rode a total of 37.2 million miles not on bike paths during the 3 year period. I gather then that drivers in DC drove 362 million miles on roads where one might find a pedestrian (i.e., excluding interstate highways, Whitehurst freeway, and New York Avenue east of Bladensburg Rd, and Rock Creek Parkway, etc.)

While not the point of this article, that is pretty impressive that cycling is 10% of what we might call "local driving".

So if cycling was about 10% of the driving but 2% of the accidents, that is an impressive difference. Too bad it is for different years, so you guess that maybe the cycling was half as great in 1997-1999, i.e., there are now twice as many ped-bike accidents. So cycling was maybe only 5% of the miles but 2% of the accidents.

Frankly, that works for me as a nice factoid (though I have rounded and would want the actual numbers). I think it is needless torture to go past that point with something like cyclists account for 20% of the time spent on roadways and 2% of the accidents.

It would be interesting to know whether pedestrians under-report accidents based on what hit them for an accident of a given severity. That would take a study. We are stuck with the data. I'm sure that very minor collisions with cyclists are overlooked, while a collision with a car is rarely trivial. But that's better left as a caveat.

So, translating for washcycle "Ugh, yeah, he is right and I have no idea what I am talking about, nor how to answer a very simple arithmatic problem, so I will avoid and obfuscate by making something up which then somehow voids me having to answer even though the question is tied to the very link I provided".

On the other hand, everyone "else" who has posted on this thread has also called you on your questionable asserts and use of unrelated data. So congrats for being your own troll.

I think I get what you're saying, but it really doesn't make any sense to me why bicycle accidents in any way compare to car accidents - particularly when pedestrians are involved.

When you walk through a intersection would you rather be struck by an idiot on a trek 1200, or an idiot in a Ford Thunderbird?

Big words can't obscure the fact that a person driving a car has a much easier time killing someone than a person riding a bicycle.

I think that Jim Titus has his finger on the problem, here: reporting. 3-year-olds, for instance, may be (and probably are) much more reckless with their tricycles than motorists are with their cars. But when a three-year-old crashes into your shin, it doesn't get reported to the police. Similarly, I would guess that many of the encounters between cyclists and pedestrians do not rise to the level where they are reported. This says very little about about cyclists and a lot about bicycles. (This is TurbineBlade's point, I think.)

guez, I tried to cover the "underreporting" problem. Maybe that wasn't clear. The underreporting would have to be huge. If 50% of car-ped crashes are reported, no more than 5% of bike-ped crashes can be reported for the conclusion to be false (so if 6% are reported the conclusion is true). In other words, I'm aware and I've addressed it. What do you think a reasonable range for the reporting rate (reported crashes/total crashes) is for these types of crashes?

I also read TurbineBlade's comment differently, but maybe he can clarify.

I guess I'm not entirely sure what I really meant, other than that I just can't compare bicycle accidents to car accidents. To say that hitting a pedestrian with a bicycle pales in comparison to hitting a pedestrian with a car doesn't even approach how absurd this comparison really is.

I guess, even if cyclists were MORE likely to crash into pedestrians (which I doubt is true) - so what? I'll just go ahead and say it.

I mainly mean this as a criticism of people who are twisting stats to make cycling seem "dangerous" to pedestrians.

If I'm crossing an intersection, once again, I'll take a PACK of idiot cyclists running the light rather than one idiot in a car doing the same thing. The same extension can be made for why tractor trailers have different speed limits, weight restrictions, and lane-use rules than passenger vehicles. It's just common sense.

TurbineBlade, I agree with everything you said. The answer to so what? is that I think it is a powerful advocacy tool if bike-ped crashes are less harmful AND less frequent. It's like choosing whether to live near someone who drives drunk once a day or bikes drunk once a week. You've got too variables pushing you to the same choice.


I have no idea what the reporting ratio is, but it would undoubtedly make the difference someone less dramatic, as would a fuller consideration of what happens on sidewalks and trails, which is where many of the complaints about cyclists (from pedestrians) come from.

I have to admit that I'm with TurbineBlade on the "so what" front. I suspect that most people are aware of the fact that cars are more of threat to life and limb than bikes. Those who are really angry at cyclists won't change their minds.

I am convinced that the whole approach to bike advocacy that seeks to refute, minimize, etc. the misbehavior of cyclists is counterproductive. The focus should not be on comparing bikes to cars, but on showing that cyclists are willing and eager to do their part to improve the culture of the road.

Guez, I'm shocked, shocked that you think that anything other than saying "we're bad cyclists and we promise to do better" is bad advocacy. Over the years, I have yet to see one concrete thing you thing we can do as bike advocacy. Really, I mean you should look back at your comments some time. There is absolutely nothing positive you have to say about anything at all. Why don't you lay out a real advocacy vision. And I mean real measurable obtainable goals. It's real easy to be the guy who says "your idea sucks", "what your doing is a waste of time", and "you're doing it wrong". It is really fucking boring and counterproductive in my opinion.

So, why don't you finally step up and show us how to do it. Anyone can be a critic guez, can you do more?

And, I think showing that CURRENT cyclist behavior makes them less likely to crash into pedestrians shows that cyclists are ALREADY doing their part to improve the culture of the road. But we don't get credit for that.

And you know what else, if your thought is "So what" than why bother making that comment? It's just so incredibly superior to drop in and say "Hey look at all this work you did. So what?" It's crap like that that makes me want to just say f--- this and walk away.

"I am convinced that the whole approach to bike advocacy that seeks to refute, minimize, etc. the misbehavior of cyclists is counterproductive."

I have not found this to be the case.

Many of my coworkers will tell me about cyclists they saw breaking the law when they're driving to and from work as a
"jib" at me, since they know I'm a daily commuter.

When I've pointed out red light camera stats, speeding stats, parking violations, etc. some of them go: "Well, yeah I guess you're right." Somtimes they kind of zone out and say something to the effect of "Well, I just don't like them getting in the way, making me late...etc."

In cases of the former, I have found that they actually now tell me about how much more PATIENT they are around cyclists because of me. I'm sure that "refuting" the criticism that it's always cyclists who break the law has had something to do with it. I of course also freely admit that many cyclists do indeed break laws, some of which can cause problems.

Oh, and as for quantifying cyclist/pedestrian problems on MUP's and trails, good luck with that one! That's where "he said, she said" stories go to die.

Guez, on the factual case (ignoring how ridiculous it is to argue the validity of the conclusion while simultaneously arguing that it doesn't matter. If it doesn't matter, then why argue that it's wrong) you'll notice that I never state the difference, only that I think it's clear that the advantage goes to the cyclists (or more accurately the bicycle. The conclusion, I suppose, is that the bicycle is a safer vehicle than a car from a crash-prevention point of view). So the magnitude of the difference is somewhat moot. I think the margin is large enough to support the conclusion. And you're unwillingness to take a stab at the report ratios further serves to undermine your position "I don't know anything about the numbers, but I'm sure you're wrong" is not a strong position. Once again, you're comfortable criticizing someone else's position, but completely unwilling to take any sort of stand FOR something.

It's interesting you bring up sidewalks and trails since some of the crashes did happen (I know this for a fact) on trails. So, the numbers consider all the reported crashes on trails, but none of the exposure. I didn't modify the numbers to account for this - so that further enlarges the margin.

As to the "so what" element I would add to the advocacy aspect the old science maxim that you can't understand what you don't measure. Knowing that bikes and the way cyclists on average ride them are safer is a valuable fact, would you not admit? If it were the other way around, would you still say "so what"? I wouldn't. I'd be here saying "look people, we need to step it up. We have ourselves to blame." But that wasn't the case. To say "so what" to any bit of science is to say "I don't think science matters" and that's something I can't agree with.

One thing your analysis is missing is any assessment of the seriousness of the collisions. Here is my rough analysis:

In February, 2007, the Washington Post reported that a pedestrian had died after colliding with a cyclist. (http://www.washingtonpost.com/wp-dyn/content/article/2007/02/03/AR2007020301735.html). The article is skimpy on any detail about the collision, but it does mention that the last reported cyclist-pedestrian fatal crash was in 1983 -- over 23 years ago. In the metro area there are roughly 400 fatalities due to
automobiles per year. So since the last time a cyclist ran into a
pedestrian and killed him, approximately 10,000 people have been killed by local motorists.

Contrarian, that is planned for later. But I will point out that the DDOT study contradicts the Post story as the DDOT study has one reported pedestrian death by bicycle crash sometime in 1998.

Because I keep track of such things there have been four such fatalities in DC since 1979.

OK, with four in 31 years we still get roughly 3,000 killed by car for each one killed by bike. I think my point still stands.

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