Tag Archives: statistics

Traffic Safety Facts: Bicyclists and Other Cyclists

[Update: the 2013 bicyclist fact sheet was released May(?) of 2015]

Each year, the USDOT, NHTSA (United States Dept of Transportation / National Highway Traffic Safety Administration) issues a report called Traffic Safety Facts: Bicyclists and Other Cyclists xxxx. The report comes out about 18 months after the close of the calendar year under review. Continue reading Traffic Safety Facts: Bicyclists and Other Cyclists

Use of alcohol as a risk factor for bicycling injury

Skip below if you’ve visited this page specifically to see the Johns Hopkins’ study.

FARS Alcohol Results

The FARS data has a number of alcohol (and drug) fields — the fields ATST_TYP, ALC_RES relate actual test type, and results. To simplify things, I’ve added a derived field sALC_RES to breaks down test results into: negative, .01 through .07, and .08+, or no results. Most fatally injured drivers, cyclists, and pedestrians do get tested. (for those that are not, there are imputed results available from a separate data file, see below).

Note that the ALC_RES field, the numerical result, has changed over the years, before 2015, it was listed as the number of hundredths of a percent BAC, e.g. 0.12 was coded as 12. In 2015 and later, it is coded as thousandths of a percent BAC, so the same result would be listed at 120.  The logic for this is encapsulated in the file 20xx_person.sql in the synthetic value sALC_RES: intox / not intox.

FARS and Drug Testing

The coding for drug results in FARS is similar to the alcohol scheme, except there are no quantitative results, only positive/negative. Also there is no equivalent to the imputation of results for drugs.

FARS coding: positive results for drugs shows up in the field DSTATUS=2 (i.e. “test given”) and DRUGRES1, 2, or 3 have a number up to 999; all in the person table. 0 meand test not given; 1 means No Drugs Reported/Negative. Potentially illicits are in groups generally in hundreds, e.g. 100-295 are narcotics, 300’s are depressants, 600’s cannaboids.  Anything 996 or above are various meanings for unknown.

Examples: Zolpidem (Ambien) is 375. See pages 579-594 of the FARS Coding and Validation Manual.

FARS and Imputation of Alcohol Results

Driving while intoxicated has been recognized as a significant serious safety factor for decades; at the same time, it’s long been recognized that many involved in fatal traffic collisions (mostly drivers but sometimes peds and bicyclists) do not have recorded alcohol test results. This nhtsa report published in 2002 explains most of the deep background and terminology on the scheme to “fill in” missing results: Continue reading Use of alcohol as a risk factor for bicycling injury

Arizona Crash Facts 2013

[ update early 2015; There are two discrepencies compared to the Crash Facts (which is still reporting 30 bicyclist fatalities at the time of this writing in Feb 2015); This will probably not be reconciled until the final FARS for 2013 is released, typically in very late 2015.  I have noted them both on the 2013 fatality grid (follow for links to news reports).  Both occurred in Lake Havasu City; which is a very peculiar. The first “missing” fatal occurred on 3/6/2013 and is present in FARS, but not asdm. This may be related to a 3/11 fatality, also in Lake Havasu City which is in both FARS and asdm.

I found a second discrepancy while googling around to find info about the 3/6/2013 fatal; so according to that there was a bicyclist fatality in the wee hours of 7/29/2013 involving a dui motorist. there’s all sorts of news coverage, the victim’s mother is on LHC city council. The driver quickly plead guilty to manslaughter and was sentenced. THIS IS NOT IN EITHER THE ASDM OR FARS!?

Also note that as of the time of this writing (early 2015) the so-called “final” FARS for 2013 hasn’t been released yet — it normally comes out in December (of 2015, for 2013). And I only have visibility into the asdm data that adot puts out on a dvd issued in June (of 2014 for the year 2013 crashes)]

Adot has released Crash Facts 2013 in early June, as usual/expected. The graphical crash map has been updated. The overall figures were relatively flat, the overall numbers of MV crashes of all types (all figures are year-over-year; 2012 vs. 2013):

  • number of MV crashes: 103,909 vs. 107,348 up 3.31%
  • all Fatalities: 821 vs.  844. up 2.80%
  • Total Injuries: 50,051 vs. 50,284 almost flat at up 0.47%

The two most closely-watched traffic safety metrics, the number of fatalities per 100M Vehicle Miles Traveled (VMT), and per 100K population are not yet available but will remain ~ 20% worse for Arizonans than for the US overall.

The results for cyclists were somewhat mixed —

  • the number of bike-MV crashes:  2,149 vs. 2,039. down 5%
  • number of cyclists injured: 1,766 vs. 1,679 down 5%
  • The number of fatalities at 30 was far higher than the last year’s 18 — the average yearly toll has been about 24; 30 is atypically high and 18 was atypically low. Fatalities, being relatively rare, have quite wide variation, making it hard to discern trends. For example in the most recent 10 year period there have been as many as 36 (in 2005) and as few as 18 (last year).

Longer term trends

I have a spreadsheet that tracks  # of cyclist injuries and fatalities for 2001-2013. The number of cyclists injured this past year, 1,679, is almost exactly at the 13-year average of 1,655; and hasn’t much varied in 13 years. We still have no good exposure data; though we can say in that time, the population of AZ has grown 24% and driving has increased 19%.  AzStats.xls (current as of 2014 data) or on google drive (the google drive version is quite possibly out of date).

Every Bicyclist Counts

I have been critical of the way the data from a recent LAB report, Every Bicyclist Counts, has been used. There is one issue, however where I am in complete agreement with LAB. The EBC used media reports and word-of-mouth to compile a list — much the same way as I do for Arizona; as of today, I am only aware of 12 Arizona bicyclist fatalities for 2013; but I now know there have been 30, so the majority are “missing”(!).  You can view the list of Arizona cyclists killed since 2009 at that same link — if you have any further information; please pass it along.  For years before 2013 the list is complete; but some victims are just placeholders, known to me only because of the crash databases.

Why are there such large gaps in media coverage?


The Arizona/Adot Safety Data Mart database (which is what i call it; i’m not sure if the CD adot sells for $15+2 is identical to that or not, but it is apparently pretty close). The CD became available mid-June on schedule and is all loaded up.

Below are some queries that match exactly “Crash Facts” for cyclists crashes/people injured, e.g. in 2013 (see chart on p.41).
Note that injury=2,3 or 4 counts Possible Injury, Injury, and incapacitating injury. The other choices are 1=No injury, 5=fatality, and (in the person table only) 99=Unknown, and somehow the unknowns always end up being no injury according to the incident table. (On spreadsheet AZstats.xls there’s a worksheet from Mike S that tallies numbers for cyclists and peds back to 2001). To count number of cyclist crashes and people, respectively:

SELECT eInjurySeverity,count(1) FROM 2013_incident i WHERE EXISTS (SELECT 1 FROM 2013_person p WHERE p.IncidentID=i.IncidentID AND p.ePersonType IN ('PEDALCYCLIST')) GROUP BY 1 ;

SELECT eInjuryStatus, count(1) from 2013_person where PersonType=3 group by 1;

Results for 2013: 2039, and 2071

To count number cyclist crashes w/injury, and number of injured cyclists:

SELECT count(1) FROM 2013_incident i WHERE EXISTS (SELECT 1 FROM 2013_person p WHERE p.IncidentID=i.IncidentID AND p.ePersonType IN ('PEDALCYCLIST')) AND InjurySeverity IN (2,3,4);
SELECT count(*) from 2013_person where ePersonType LIKE 'PEDAL%' AND InjuryStatus IN (2,3,4) ;

results for 2013: 1669 and 1679

Brief Remarks on 2014 Crash Facts

From Page 1 of 2014 Crash Facts; of the 884 total persons killed in Arizona traffic crashes:

  • Motorists: 589 (= 425 drivers + 164 passengers)
  • Pedestrians: 157
  • Pedalcyclists: 28


Is it really 20 times more dangerous?

I’ve been seeing, more often lately it seems, fairly bold numerical statements about relative bike traffic safety; so to take this one from peopleforbikes for example (my emphasis added): “The problem is particularly glaring here in the United States, where bike injury and fatality rates are roughly 20 times those of the cycling-friendly countries of western Europe“. Continue reading Is it really 20 times more dangerous?

Arizona Bicyclist and Ped Crash Map

2009-2016 Arizona Traffic Crash Map:


  • The map covers reported traffic collisions; involving a bicyclist, or pedestrian, respectively. The general reporting requirements are any collision w/any injury or > $1,000 worth of property damage occurring on a public road involving a motor vehicle (so for example, a bike-bike, or a bike-ped collision isn’t going to be reported here. It is well established that the lesser the severity, the more under-reporting there is. [for expediency/laziness sake, the peds, but not the bicyclists, only include incidents with exactly one MV and exactly one ped — this limits the amount of “hand” editing that needed to be done. As a result ~ 4% of ped incidents are not on the map]
  • Motorized bicycles are generally categorized as a motorcycle and as such don’t appear here.
  • There is no “exposure”; each crash is represented by a dot on the map, end of story. There are, of course, many more dots where more people live and bike/walk and vice versa.
  • The key to the dot color for injury severity is as  follows: green-No Injury, blue-Possible Injury, yellow-Non Incapacitating Injury, red-Incapacitating Injury, b/w larger target-Fatality. There is a second map keyed by whether a crash was a hit and run (red means it was).
  • A small number of crashes have no GIS data, and are not on the map. For example;  2009-2013 there are 9,982 bike-MV crashes of which 324 (about 3%) have no latitude/longitude. [I think somebody ought to find out why the number of zeros is so high again in 2013!? 2012 saw a total of 663 (out of something over 100,000), less than 1% and seems acceptable. But 2013 shot up to 2,905!! Why so many?]

crashmapAbout the Data

The underlying data comes from ADOT; each year they release a public dataset with codified information for each of the ~ 100,000 (actually, over 125,000 for 2016!) reportable Motor Vehicle crashes. This data is sometimes/also referred to as the ASDM (Adot Safety Data Mart). Currently, 2016 is the most recent year available; and 2009 is the oldest (the oldest data I have, older data is available from Adot).

Of these, about 2,000/yr crashes involve a bicyclist (this number has fallen in recent years to  below 1,500) , and for comparison about 1,500 involve a pedestrian. The pedestrians suffer far more serious injuries and fatalities, however.

For presentation purposes, many, but not all,  of the data fields are extracted and stored in a google fusion table. Because of technical constraints on the way fusion tables are implemented; crashes involving more than one bicyclist or more than one motorist are not completely described. This is a small minority of crashes.

Continue reading Arizona Bicyclist and Ped Crash Map

Collision Manner

[Warning/correction not yet made: in the table below where it says MV-only, that’s not quite correct, it’s really incidents where no pedalscylists are involved. The MV-only calculations should also exclude pedestrians; this can be accomplished by saying u.eUnitType LIKE ‘PED%’  In the query below i corrected it but didn’t correct the table; the percentages don’t really change since there are relatively few ped crashes ]

Here is a breakdown of Collision Manner, and rates, for MV collisions (i.e. one or more MV, and not involving a ped or bicyclists) compared to bike-MV collisions.

The megatrends are that rear end collisions are, by far, the predominant manner of collision for MVonly crashes; wheres for bike-MV crashes this manner is quite infrequent — almost twelve times more frequent. For bike-MV crashes, the predominant manner is angle, i.e. so called “turning and crossing” movements (although left turn is broken out as a separate manner).

The 38% rate of REAR END crashes for MVs actually understates the rate — if you back out the number of SINGLE VEHICLE crashes; you see that nearly half of all multi-car collisions are REAR END(!). 38,499/(101,055 – 18,647) = 47%. Inattention? Does this mean that motorists actually are more attentive to same-direction traffic when it’s a bicyclist, compared to another motorist? hmmm.

| eCollisionManner             | MVonly| MVrate |bikeMV|bikerate|MV:bike ratio|
| REAR_TO_REAR                 |   287 | 0.0028 | NULL |   NULL |        NULL |
| UNKNOWN_99                   |   859 | 0.0085 |   40 | 0.0189 |  0.44973545 |
| REAR_TO_SIDE                 |   895 | 0.0089 |   11 | 0.0052 |  1.71153846 |
| SIDESWIPE_OPPOSITE_DIRECTION |  1244 | 0.0123 |   46 | 0.0217 |  0.56682028 |
| HEAD_ON                      |  1438 | 0.0142 |   45 | 0.0212 |  0.66981132 |
| OTHER_97                     |  3160 | 0.0313 |  404 | 0.1905 |  0.16430446 |
| SIDESWIPE_SAME_DIRECTION     | 10727 | 0.1062 |  124 | 0.0585 |  1.81538462 |
| LEFT_TURN                    | 11888 | 0.1176 |  189 | 0.0891 |  1.31986532 |
| ANGLE_FRONT_TO_SIDE          | 13411 | 0.1327 | 1194 | 0.5629 |  0.23574347 |
| SINGLE_VEHICLE               | 18647 | 0.1845 | NULL |   NULL |        NULL |
| REAR_END                     | 38499 | 0.3810 |   68 | 0.0321 | 11.86915888 |
total num of MVonly crashes = 101,055.  total num of bike-MV crashes = 2,121
source: 2012 ASDM

Continue reading Collision Manner

Arizona road-safety focus switches to pedestrians

… or so says the headline. Arizona road-safety focus switches to pedestrians, by Jim Walsh, The Arizona Republic Oct 11, 2012.

The article looks at the uncomfortable truth in Arizona traffic crash stats — that ped rates appear to have gotten worse even as MV rates have fallen (see ‘Disturbing Trend?’ here). The article neglects to mention that Arizona trends worse than average in overall (overall US; and overall counting motorist, pedestrian and bicyclist) traffic fatalities.

Why is Phoenix Dangerous by Design? As I pointed out when the 2010 Arizona statistics came out: “there were more bicyclists killed within the City of Phoenix (9) than were killed in the entire state of Massachusetts(6)”; it appears that Arizona/Phoenix values building out more ultra-wide (lots of lanes), ultra-fast (speeds 40mph AND UP). These car sewers are not conducive to human life; and that goes for not only pedestrians but for bicyclists and motorists as well. This is also the gist of the paper/article Beyond Safety in Numbers: Why Bike Friendly Cities are Safer.

To complete the factoid: Nearly as many pedestrians were killed in the city of Phoenix (45) than in the entire state of Massachusetts (56) in 2010. (sources: City of Phoenix 2010 Traffic Collision summary; NHTSA State Traffic Safety Information for the year 2010).

We’re doing something horribly wrong here in Arizona.

To Continue The Theme…

A more recent article then appeared a couple of weeks later  Pedestrian vs. vehicle fatalities alarm police, By Cecilia Chan, The Arizona Republic,  Nov 12, 2012.

There’s a bit of undertone from certain parties that this is largely a pedestrian problem, e.g. Phoenix police spokesman James Holmes said. “Lots of accidents are midblock”. There are a couple of problems with this attitude — one is that with long blocks (the norm on Phoenix’s arterial streets), traffic both speeds up, and there is simply more mid-block (that is to say, it becomes increasingly unreasonable for a pedestrian to walk out of their way to a crosswalk).

Setting all that aside, reading on we find that (only)” Thirty percent of the fatal pedestrian collisions in 2010 were the result of the pedestrian not using a crosswalk”, and “In 49 percent of the fatal collisions, the driver was not at fault”. Which is to say: 70 percent of peds in collisions were using a crosswalk, and right around half the time the ped is at fault (even under the laws, that clearly fault peds over motorists, particularly at mid-block), and the other half the time the motorist was at fault.


Arizona Road Deaths Increase — 2011 data

ADOT recently released 2011 Crash Facts.

In summary: The overall traffic death toll bounced up after several years of significant declines. The number of fatalities is up 9% year-over-year, despite a 3% decrease in the number of crashes.

Year over year: ped injuries and fatalites were nearly flat; bicyclist injuries were also nearly identical. There were 23 cyclists killed in 2011 (versus 19 in 2010)

Here’s a news piece: azcentral.com/news/articles/20120816arizona-road-deaths-increase It has a graph of fatals per 100million VMT which appears to be drawn wrong; for example line chart shows Arizona’s virtually on top of the overall-US figure for 2009, and 2010 but that’s not correct; although in recent years Arizona has been closing the gap, it remains markedly higher than overall-US:

2009: 1.14 vs. 1.31

2010: 1.11 vs. 1.27

It’s a pretty small graph but it’s clearly not right — the Arizona Line is drawn incorrectly for those two years.