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Old 06-09-2020, 01:31 PM   #16
DataDan
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Quote:
Originally Posted by motomania2007 View Post
Dan, does your alcohol involvement data mean .08 BAC (legally drunk) and higher or just measurable BAC (impaired and drunk rather than just legally drunk)?
It's either measured BAC > 0, or assessed by the investigating officer as had been drinking (but not necessarily impaired).

If the rider is killed, there is often BAC from an autopsy. In California, more than 80% of deceased riders have BAC reported (even if 0); in other states it can be less.

In other cases, the investigator usually makes a judgment call on whether the rider had been drinking.

Data is from three source: FARS, the USDOT fatality database; CRSS, the USDOT crash sampling system; and SWITRS, the CHP database of all California crashes. FARS and CRSS use BAC if reported, officer assessment if not. SWITRS uses only officer assessment.
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Old 06-09-2020, 01:55 PM   #17
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Quote:
Originally Posted by budman View Post
Thanks DD.
The flattening mentioned is good.. more training? More..
My opinion is that the flattening of the US fatality rate curve post-recession resulted from the end of the motorcycling boom. I'll get into this a bit more tomorrow, but my theory hypothesis conjecture wild-ass guess is that crash and fatality rates move in the same direction as growth in the sport--up when growing, down when declining.

When the popularity of motorcycling is increasing, the noob percentage is high and, consequently, average experience falls. On the other side of the boom--the bust, such as in the early 1990s--fewer noobs means higher average experience. Because greater experience decreases crash risk (seen both in Hurt and MAIDS), the crash rate curve will follow the sales curve.
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Old 06-09-2020, 01:59 PM   #18
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Quote:
Originally Posted by DataDan View Post
It's either measured BAC > 0, or assessed by the investigating officer as had been drinking (but not necessarily impaired).

If the rider is killed, there is often BAC from an autopsy. In California, more than 80% of deceased riders have BAC reported (even if 0); in other states it can be less.

In other cases, the investigator usually makes a judgment call on whether the rider had been drinking.

Data is from three source: FARS, the USDOT fatality database; CRSS, the USDOT crash sampling system; and SWITRS, the CHP database of all California crashes. FARS and CRSS use BAC if reported, officer assessment if not. SWITRS uses only officer assessment.
When you say "80% of deceased riders have BAC reported" does that mean 80% of deceased riders have a positive BAC <0 or that only 80% have a BAC data filled in and some (most?) of them are reported at 0%?
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Old 06-09-2020, 02:54 PM   #19
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Quote:
Originally Posted by motomania2007 View Post
When you say "80% of deceased riders have BAC reported" does that mean 80% of deceased riders have a positive BAC <0 or that only 80% have a BAC data filled in and some (most?) of them are reported at 0%?
California Motorcycle Riders Killed by BAC

0.000 .001-.079 .080-.149 .150+ not reported % reported
.......... ................ ................ ................ ................ .................... ....................
1990 239 54 61 129 45 91%
1991 218 40 54 90 45 90%
1992 173 19 28 62 24 92%
1993 164 15 36 42 38 87%
1994 137 24 46 36 28 90%
1995 129 22 23 47 25 90%
1996 115 15 24 40 27 88%
1997 120 14 26 37 24 89%
1998 106 11 18 39 18 91%
1999 132 10 23 30 25 89%
2000 148 17 24 34 35 86%
2001 177 21 22 38 18 93%
2002 190 23 27 37 30 90%
2003 223 18 29 52 35 90%
2004 257 20 27 59 42 90%
2005 276 22 28 55 73 84%
2006 293 30 42 62 49 90%
2007 319 28 30 78 41 92%
2008 336 20 50 83 48 91%
2009 255 16 34 49 31 92%
2010 207 24 27 57 25 92%
2011 231 28 29 49 50 87%
2012 266 22 26 66 46 89%
2013 274 30 32 67 42 91%
2014 289 27 41 80 66 87%
2015 274 68 22 53 60 87%
2016 336 30 47 75 64 88%
2017 329 37 35 90 71 87%
2018 208 19 28 44 173 63%

"Not reported" includes: not tested, tested but results unknown, unknown if tested, and not reported.

The reported % for 2018 is low because it's from the first database release. The final usually comes out in October.

Data for this table is from the US DOT fatality database, which includes all riders involved in fatal crashes. Around 10% of riders in fatal crashes survive (passenger, another rider, or non-motorcyclist killed), and only about 20% of those have BAC reported.
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Old 06-10-2020, 12:13 PM   #20
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Crash Lethality

In yesterday's post I tried to show that the motorcycle fatality rate per registered bike increased as the sport grew quickly from the late 1990s until the recession hit in 2008. Maybe this was caused by a rising crash rate--more crashes, more deaths? No. A graph back in post #6 showed that crash rate had not climbed that way. In fact, it declined in the early 1990s then flattened through the early 2000s. What gives?

Another way to look at fatality rate is as a combination of crash rate and crash lethality--the percentage of motorcycles involved in crashes multiplied by the percentage of crashes that kill the motorcyclist. If 2% of registered motorcycles crashed over a year's time, and 3% of those crashes resulted in death, then 0.06% of motorcycles were involved in a fatal crash. Crash lethality helps explain the apparent contradiction between a falling crash rate and a rising fatality rate.

This graph shows three plots for the US since 1990. Fatality rate (gray shaded area) is the same as in yesterday's post. But instead of showing it along with registrations and deaths, I've combined it with crash rate (gold) and crash lethality (blue).



At first, crash rate and fatality rate declined in parallel as the motorcycle depression of the 1990s came to an end. A lot of factors surely contributed--the spread of training, more capable motorcycles, greater safety awareness among riders. Another factor I suspect is related directly to the decline of motorcycling. As the sport collapsed in the late 1980s, sales dropped by nearly two-thirds, so there were fewer new riders and proportionally more veterans on the road. Because of this, average motorcyclist experience was up, and we know from the Hurt and MAIDS crash studies that experience substantially reduces crash risk.

However, when the motorcycling resurgence began in the late 1990s, crash rate flattened out but the fatality rate reversed and began to climb. This was because motorcycle crashes were becoming more deadly. In the early 1990s, before the boom kicked off, the lethality rate was already climbing. From a low of 30 deaths per 1000 crashes in 1992, it rose by more than one-third in less than 10 years and continued to increase until the recession hit. By then, crash rate was near an all-time low, but, driven by crash lethality, the fatality rate was higher than it had been in more than 15 years.

When the boom came to an end in 2008, the fatality rate dropped by 25% in four years, drawn down by a similar decline in crash rate, and that is how it has remained through 2018. My hunch is that the recent crash rate drop was, again, the noob/vet effect--fewer new riders, more veterans, lower average risk. Unfortunately, our all-time low crash rate--20% less than post-depression low of 1999-2000--has not been accompanied by an all-time low fatality rate. High crash lethality has kept that achievement out of reach.

Tomorrow I will identify factors that have driven crash lethality to its current high level and will keep it there for the near future.


California and the Bay Area

The California graph of fatality rate, crash rate, and crash lethality is similar to the US, so my previous analysis applies, at least generally. However, I do want to point out some differences.



My confidence in California crash counts for the 1990s isn't real high, so neither is my confidence in crash rate and lethality. However, I feel pretty good about crash counts from 2000 forward. I am much more confident about registrations and fatalities, so I trust fatality rate over the entire range.

Notice that the California crash rate (gold line) is higher than the US--most likely due to our year-round riding--while lethality (blue line) is lower--probably due to the helmet law. Yet the fatality rate (gray shaded area) for both is in the neighborhood of 60 deaths per 100,000 registrations. End result is the same, but contributing factors differ.

The precipitous drop in fatality rate from 1990 to 1994 is due to two big factors: First, the training requirement for riders < age 21 went into effect in 1991 (the < 18 requirement began in 1987). Whether training made them safer or dissuaded them from taking up the sport in the first place is more of a philosophical question at this point. Whatever. Young riders were a big demographic in the sport in 1990, so the training requirement very likely prevented crashes. Second, the all-rider helmet law went into effect January 1, 1992. Again the question is dissuasion or prevention, but it certainly saved lives.

Compared to the US, California's fatality rate dropped more sharply at the onset of the recession in 2008, and while the US rate has been flat since, California's increased, though not revisiting the pre-recession high. Notice that crash rate and crash lethality have both driven California's post-recession fatality rate higher since 2011.




Again my lack of registration data limits conclusions about the Bay Area. Worth noting, however, is that the crash rate, crash lethality, and fatality rate are all quite a bit lower than statewide. I have no explanation for the fact that the 2007-2008 fatality peak was a product of crash lethality rather than crash rate. I have piles of data on those years but haven't dug into it to find an answer. Post-recession, the crash rate mostly paralleled the rest of the state, but lethality remained much lower. One guess about the lower lethality is that many Bay crashes are low-speed freeway and city incidents that usually don't seriously injure the rider.
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__________________
How can I help seeing what is in front of my eyes? Two and two are four.
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Last edited by DataDan; 06-13-2020 at 10:35 AM..
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Old 06-11-2020, 10:26 AM   #21
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Why have motorcycle crashes become deadlier?

The surprising conclusion from yesterday's post is that motorcycle crashes in the US and in California are more likely to be fatal now than they were 30 years ago. The percentage is low--only 4% of US crashes and 3% of California crashes take the life of the rider--but still, this seems contrary to what we know about the sport. Protective gear, improved and worn much more often than 30 years ago, should be reducing crash lethality.




However, since 1997 all-rider helmet laws have been repealed in six states, including four of the top 10 US motorcycle states. Has reduced helmet use increased crash lethality?



Seems not. In spite of the repeals, helmet use has been gradually rising, not falling. Even in states with no helmet requirement, helmet use has increased. In Michigan, the most recent repeal, 70% of crash-involved riders are wearing one. In Texas it's 59%, in Florida 55%.


Older riders are more vulnerable riders

After discovering the lethality increase a few years ago, I wondered if it had resulted from more violent crashes. Maybe brave young riders on 180mph sportbikes had inflated the fatality data. That guess was crushed when I found that young riders, particularly those under age 25, were at less risk of dying in the event of a crash than older riders. Digging deeper, I found that the 55+ age group, not the < 25 group, was pushing lethality higher.



And the 55+ age group has been growing for 30 years:



Since 1990, 26% of motorcyclists involved in crashes in the US have moved statistically from the least vulnerable age group--the under 25s--into more vulnerable groups, most of them into the most vulnerable groups. This accounts for a substantial part of the lethality increase.

In post #9 of this thread, I concluded that growth in the 55+ age group had reduced the crash rate. Increased crash lethality is the downside of that change.


Lethality by age in California is similar to the US:



My detailed California crash data includes rider age back only to 2001, so I can't present an age distribution graph that includes earlier years, but what I have does show that the percentage of crash-involved riders age 55+ doubled from 2001 to 2018:




A more deadly mix of vehicles on the road

Over the past 30 years, the typical family transportation appliance has morphed from a Taurus or Accord into an F-150, Odyssey, or Suburban. This has not been a welcome development for motorcyclists, because the latter group--classified as light trucks by NHTSA--is much less crash-friendly to us. The late Wendy Moon wrote about the impact of this shift in a 2004 Motorcycle Consumer News article, "Fatal Design", and I have kept track of the relevant crash data subsequently.



In 1990, light trucks--pickups, vans, minivans, SUVs, crossovers--comprised less than 20% of vehicles involved in 2-vehicle motorcycle crashes, but accounted for 32% of the rider deaths that occurred in those crashes. In that same year, cars accounted for 75% of crashes and 55% of deaths. Since then, light truck involvement has increased to 37% of crashes and 45% of deaths. Clearly, the difference in motorcyclist crash lethality between cars and light trucks is huge:




Conclusion

In spite of improvements in motorcycle protective gear and its growing use, crashing has become more deadly over the past 30 years. The observed increase in motorcycle crash lethality can be explained in substantial part by the aging riding population and the mix of other vehicles on the road. Neither of those factors is likely to change in the foreseeable future.

Motorcyclist median age seems to have stabilized in the late 40s. It has gone from a young man's sport to one that appeals to men and women over a wide age range. While crash risk is lower thanks to the presence of older, more conservative riders, vulnerability to fatal injury has increased due to the same change in age distribution.

For a variety of reasons, Americans enjoy big vehicles to transport themselves and their families. Fifty years ago it was a Buick Electra Deuce-and-a-Quarter. Today, it's a Ford F-350 or Mercedes GLS or whatever, which poses serious danger to a motorcyclist in the event of a crash. The increase in light trucks from < 20% of multiple-vehicle motorcycle crashes 30 years ago to 37% today has resulted in an additional 280 rider deaths per year by my estimate. In no feasible scenario will these vehicles soon become either less popular or less deadly.
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Last edited by DataDan; 06-11-2020 at 02:12 PM..
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Old 06-12-2020, 06:56 AM   #22
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tl;dr

Here's a summary of my main posts in this thread. Links are to those posts.

That's it for me. I have no more posts planned for this thread, but I will be glad to answer any questions you have, so post them up.

I haven't cited sources, but everything that appears is from a federal or California government publication. If you have a question on the data, send me a PM and I'll reply with a link or document.
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Old 06-12-2020, 08:08 AM   #23
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Thanks for the education!

I like learning the data.

Not all great news but facts are important, whether good or bad.
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Old 06-12-2020, 09:36 AM   #24
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Thanks for the summary Dan.

Makes it easier to catch up again later.
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Old 06-18-2020, 08:47 AM   #25
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Quote:
Originally Posted by DataDan View Post

For a variety of reasons, Americans enjoy big vehicles to transport themselves and their families. Fifty years ago it was a Buick Electra Deuce-and-a-Quarter. Today, it's a Ford F-350 or Mercedes GLS or whatever, which poses serious danger to a motorcyclist in the event of a crash. The increase in light trucks from < 20% of multiple-vehicle motorcycle crashes 30 years ago to 37% today has resulted in an additional 280 rider deaths per year by my estimate. In no feasible scenario will these vehicles soon become either less popular or less deadly.
Good stuff Dan.

My Dad had an Electra 225 he bought in 1966, the year I came to this Country from the UK.

I read an article in an actual moto rag many moons ago how much more dangerous to a rider hitting the side of an SUV was compared to hitting the side of a car.

Maybe it was MCN?
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Old 06-18-2020, 10:08 AM   #26
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Good stuff Dan.

My Dad had an Electra 225 he bought in 1966, the year I came to this Country from the UK.

I read an article in an actual moto rag many moons ago how much more dangerous to a rider hitting the side of an SUV was compared to hitting the side of a car.

Maybe it was MCN?
Probably so. MCN ran "Fatal Design" by Wendy Moon in the July 2004 issue.

It didn't get as much attention as expected. ISTR that editor Fred Rau had promoted it on the MCN forum as a big deal. However, she implausibly exaggerated the number of motorcyclist deaths due to the shift to light trucks, and there were some errors and ambiguities in the graphics presented with the article. I was highly skeptical at the time.

However, I did start keeping track of 2-vehicle motorcycle crashes and eventually (years later) came to agree that the effect is real, though estimating a much more modest magnitude.
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