Latest Safety / Stat info stuff from California

[DataDan]

This is really interesting stuff Dan.

Love to hear you take on the different regions.

I don't know. Maybe traffic density in LA and the Bay Area tends to produce more low-speed, non-life-threatening crashes, while the wide-open spaces in the San Joaquin Valley and Inland Empire create more potentially deadly conditions. :dunno

Or maybe something related to demographics, but I'm not going there.

 

[DataDan]

Specifically I am interested in alcohol use, sex, and location if I had to pick a top three...

Alcohol use gets a lot of attention, of course, but statistically it's not as big a crash factor as it is perceived to be. I'm not saying that alcohol impairment doesn't increase the chance of a crash. I mean that fewer motorcyclists drink and crash than some think.

In nearly all non-fatal crashes, the LEO assesses whether the rider had been drinking and whether he was impaired. This isn't a breath or blood test, but a judgment call. The following, from the CHP SWITRS database, is based on 65,000+ non-fatal crashes in California 2011-2015:

In fatal crashes, OTOH, the rider's blood alcohol content is entered into the US DOT's traffic fatality database. In California motorcycle fatalities, BAC is reported for about 80% of riders. This graph is based on 1800+ riders in fatal crashes 2011-2015:

Note that the .01-.07 contribution is relatively small (6.5%) while the .15+ contribution is large (17%). So a lower BAC limit for motorcyclists--a .05 standard has been suggested--would not address the greater problem of seriously drunk riders.

CMSP's Total Control Training mistakenly teaches that 52% of California riders in fatal crashes have BAC .01 or higher. In fact, it's closer to 30% as shown above.

 

[ctwo]

I think there are some problems with reporting. For example, none of my crashes that happened in the <25 age were reported. It seems most youths that crash are quick to jump up off the road and run to their bike to avoid the embarrassment. You get a little older, wiser, and more fragile and you end up with a report.

Cops are human too and I can see them giving some leniency or overlook a relatively non-serious concern. I wonder if a test should be automatic for survivors as well, and consideration of automatic DUI charges with BAC 0.01+.

 

[LittleBigGirl]

Cool, thank you for sharing this!

It is motion immediately before impact, such as: "going straight", "turning left", "passing", "merging", etc.


I'll put something together in a day or two. For now, here are two from recent work:

Annual Bay Area crashes increased by one-third from the recession low in 2010 to 2015 (this includes all police-reported motorcycle crashes from non-injury to fatal). Which age groups were most affected?

Crash lethality, the likelihood of a motorcycle crash killing the rider, differs by age group, as one might expect. But in California, with all of its geographic and demographic variation, it also differs by region:

This graph shows the percentage of riders (passengers excluded) who died in police-reported crashes. Regions are:

• Sacramento Valley: counties on the I-5 corridor from Sacramento to Redding
• Bay Area: 9 counties on the Bay + Santa Cruz
• Central Coast: Ventura to Monterey plus San Benito
• San Joaquin Valley: I-5 corridor from the Grapevine to Stockton
• El Lay: Los Angeles and Orange Counties
• Inland Empire: Riverside and San Bernardino Counties
• Sandy Eggo: San Diego and Imperial Counties

 

[LittleBigGirl]

Interesting points.

I think there are some problems with reporting. For example, none of my crashes that happened in the <25 age were reported. It seems most youths that crash are quick to jump up off the road and run to their bike to avoid the embarrassment. You get a little older, wiser, and more fragile and you end up with a report.

Cops are human too and I can see them giving some leniency or overlook a relatively non-serious concern. I wonder if a test should be automatic for survivors as well, and consideration of automatic DUI charges with BAC 0.01+.

 

[glooey]

I have recently reorganized my copy of the SWITRS database thru 2015 to more easily summarize moto-related stuff. If there's something specific you're interested in, I may be able to post a table or graph I already have or can produce quickly.

For info, here are a few of the data elements collected for every crash: date, time, location (city, county, road, milepoint, sometimes lat/lon), weather, crash severity (from fatal to non-injury), who was at fault, primary collision factor, type of collision (head-on, rear-end, etc.), types of vehicles involved. For each vehicle: driver age, sex, drug/alcohol use, injury severity, helmet, movement before crash, other contributing factors. There's not much about the motorcycle itself other than make.

Anything there you'd like to see?

For "rear-end" collisions, are you able to parse among 1) motorcycle rear-ended (motorcycle hit from behind), 2) motorcycle rear-ender (moto hit another vehicle's rear), and between a) lane splitting and b) not splitting?

Thanks.

 

[DataDan]

For "rear-end" collisions, are you able to parse among 1) motorcycle rear-ended (motorcycle hit from behind), 2) motorcycle rear-ender (moto hit another vehicle's rear), and between a) lane splitting and b) not splitting?

Thanks.

In fatal crashes, the US DOT database reports clearly which vehicle did what in a rear-end crash. In California fatal 2-vehicle rear-end crashes 2011-2015, the motorcycle struck the other vehicle from behind in 82% of cases. For the US (including California) it was 64%.

But the 161 California fatals are just a small percentage of all rear-end crashes. On the CHP SWITRS database, there are more than 10,000 2-vehicle motorcycle rear-end crashes 2011-2015. In that data, it's less clear who did what to whom. "At fault" is reported, and the rider was at fault in 64% of those crashes. In most of those, I expect the motorcycle struck the other vehicle from behind, but there's also the possibility that the rider was at fault for a crap lane change that precipitated impact from behind.


Lane splitting is not reported in either the US DOT traffic fatality database or CHP's SWITRS.

 

[glooey]

Thanks, DataDan.

 

[DataDan]

2016 update

I've recently downloaded 2016 crash data from the CHP website. Here are summaries for California and the Bay Area (= 9 counties on the Bay + Santa Cruz):

crash data from http://iswitrs.chp.ca.gov/Reports/jsp/RawData.jsp

While crashes have increased post-recession, fatalities are below the 2008 highs both statewide and in the Bay.

So far in 2017, we have seen a lot of BARF RIP threads. From stories that have appeared in the news, 39 riders have died year to date, more than the database count for the same period in 2016 but about the same as 2015.

 

[burtosa]

This is fantastic, super interesting, and important info! Thank you for sharing!

 

[berth]

These recent graphs are totals, or per capita/per mile traveled, or some other "normalizing" statistic?

 

[NorCalBusa]

These recent graphs are totals, or per capita/per mile traveled, or some other "normalizing" statistic?

An important suggestion. :afm199 :thumbup

 

[DataDan]

These recent graphs are totals, or per capita/per mile traveled, or some other "normalizing" statistic?

Numbers in the 2016 update are counts--around 17,000 police-reported motorcycle crashes in California in 2016.

Crash rate per vehicle-mile traveled is the best way to assess average motorcyclist risk IMHO, but motorcycle vehicle-mile estimates by state aren't very reliable. Motorcycle registrations, OTOH, are reliable but may not reflect actual riding. However, registrations is the best exposure measure available, and assuming riding habits don't change dramatically year-to-year, the rate can help spot short-term trends.

Here is a recent history of crashes, registrations, and crash rate per 1,000 registrations (2016 registrations are not yet available). I included Bay Area data in my 2016 Update post, but motorcycle registrations by county are no longer available, so I can't present the Bay Area rate.

crash data from http://iswitrs.chp.ca.gov/Reports/jsp/RawData.jsp
registrations from https://www.fhwa.dot.gov/policyinformation/statistics.cfm


Another aspect of crash risk is lethality, the percentage of reported motorcycle crashes that result in rider death:

crash and fatality data from http://iswitrs.chp.ca.gov/Reports/jsp/RawData.jsp

 

[stunna]

Numbers in the 2016 update are counts--around 17,000 police-reported motorcycle crashes in California in 2016.

Crash rate per vehicle-mile traveled is the best way to assess average motorcyclist risk IMHO, but motorcycle vehicle-mile estimates by state aren't very reliable. Motorcycle registrations, OTOH, are reliable but may not reflect actual riding. However, registrations is the best exposure measure available, and assuming riding habits don't change dramatically year-to-year, the rate can help spot short-term trends.

Here is a recent history of crashes, registrations, and crash rate per 1,000 registrations (2016 registrations are not yet available). I included Bay Area data in my 2016 Update post, but motorcycle registrations by county are no longer available, so I can't present the Bay Area rate.

crash data from http://iswitrs.chp.ca.gov/Reports/jsp/RawData.jsp
registrations from https://www.fhwa.dot.gov/policyinformation/statistics.cfm


Another aspect of crash risk is lethality, the percentage of reported motorcycle crashes that result in rider death:

crash and fatality data from http://iswitrs.chp.ca.gov/Reports/jsp/RawData.jsp

Thx for the summary DD. :thumbup

 

[Schnellbandit]

Q: I have witnessed on more than one occasion a motorcycle go down and the rider gets back on the bike and takes off (could be for many different reasons). In both instances there was no collision although that isn't to say one would not have happened or the reaction to an impending collision didn't result in the reaction that caused the single vehicle crash.

Does this happen enough to consider that there would be a meaningful affect to the stats? I recognize that the rider probably isn't calling it in, but do others?

If the Q is inappropriate for this thread, Op can say so, I'll zap it.

 

[DataDan]

Q: I have witnessed on more than one occasion a motorcycle go down and the rider gets back on the bike and takes off (could be for many different reasons). In both instances there was no collision although that isn't to say one would not have happened or the reaction to an impending collision didn't result in the reaction that caused the single vehicle crash.

Does this happen enough to consider that there would be a meaningful affect to the stats? I recognize that the rider probably isn't calling it in, but do others?

If the Q is inappropriate for this thread, Op can say so, I'll zap it.

Good question, but I don't have a good answer.

It's happened to me a few times in the past 40 years. I'm not going to file a police report for a solo crash without good reason--damage to someone else's property, damage to the motorcycle I want insurance to cover, or injury to me.

While inclusion of incidents like that would increase crash counts, I don't think they would affect trends, since the unreported crash percentage probably doesn't change year-to-year.

Here are updated versions of the charts I posted in 2017:

 

[cal scott]

It's interesting to see that the number of crashes (adjusted for ridership) and rider lethality have remained relatively constant over the time frame presented. Although I don't have any data to hand, I would expect that a much larger percentage of bikes now have various rider aids (ABS, traction control etc.). If this were true, that would indicate that, despite the broader adoption of newer technologies to prevent crashes, this hasn't had much of an impact in the number of actual crashes or rider deaths. Is this a fair conclusion?

 

[DataDan]

It's interesting to see that the number of crashes (adjusted for ridership) and rider lethality have remained relatively constant over the time frame presented. Although I don't have any data to hand, I would expect that a much larger percentage of bikes now have various rider aids (ABS, traction control etc.). If this were true, that would indicate that, despite the broader adoption of newer technologies to prevent crashes, this hasn't had much of an impact in the number of actual crashes or rider deaths. Is this a fair conclusion?

The effect of ABS doesn't show up in data like this because ABS is still not very widely used, and the kinds of crashes it can prevent are not a large percentage of all crashes.

An NTSB analysis (PDF) of the as-yet unpublished Motorcycle Crash Causation Study found:

Non-ABS-equipped motorcycles had 2 times the crash risk relative to motorcycles that had this safety feature. The percentage of MCCS motorcycles that were equipped with ABS (11%) was consistent with that of all registered motorcycles with ABS as a standard or optional feature in the United States (12%) in 2015.​

A 50% reduction in crash risk sounds like a lot. But that was for all crashes, not only those where ABS would help. So part of the observed benefit is due to the tendency of riders who buy ABS to be safer in other ways, too.

Hurt found slide-out or highside (presumably the result of initial lockup) in 24% of crashes. I looked at one year of NHTSA's Crash Report Sampling System and found that a skid occurred in 14% of crashes. Going with Hurt's result and the reported 12% presence of ABS, crashes would be reduced by less than 3%.