Pedestrian and bicycle safety data analysis

If you spend much time perusing the available safety publications for Michigan, it becomes fairly evident that not much serious effort is put into bicycle and pedestrian analysis.

SEMCOG

One example is SEMCOG’s Crash Facts report where more analysis and pages are devoted to vehicle-deer crashes than either pedestrian crashes or bicycle crashes. This is despite the fact that deer caused just one driver fatality in 2007. There were 65 pedestrian fatalities and 7 bicyclist fatalities in 2007.

For 2008, SEMCOG issued a cheery press release because overall fatalities and crashes were down.

“We are extremely happy to report this continuing decline in traffic crashes in Southeast Michigan,” notes SEMCOG Executive Director Paul Tait.

SEMCOG failed to note that both bicycle and pedestrian fatalities were up. In fact, 18% of all fatalities were pedestrians and bicyclists in 2007. In 2008 that pecentage jumped to 24%.

It seems the “analysis” is simply plugging this year’s numbers into the same old template.

A worthwhile analysis would look at trends within the region and where within the roadway these crashes are occuring.

Do we really need SEMCOG telling us that “bicycle crashes were more common in warmer months…likely due to the difficulties of bicycling in snowy or icy conditions?” They’ve been recycling this same text since 2002.

MDOT

To their credit, MDOT has supported some pedestrian safety studies within the city of Detroit. The city of Detroit’s Traffic Engineering department is has applied for safety funding to make improvements that should reduced pedestrian crashes.

GTSAC

Also, the Governor’s Traffic Safety Advisory Council includes some good analysis within the Michigan Pedestrian and Bicycle Safety Action Plan.

Michigan Pedestrian and Bicycle Safety
Action Plan

OHSP

One interesting analysis from the Office of Highway Safety Planning (OHSP) compares 2007 bicycle crash injury severity for helmeted and non-helmeted riders. We’ve rebuilt their data table as follows:

2007 Bicycle Crashes Total crashes Fatal or serious injury Minor or no injury
With helmet 177 18% 46%
No helmet 795 10% 51%

(Note that it is unreported whether helmets were worn in a little over half of the crashes.)

Among bicyclists wearing helmets in crashes, a significantly higher percentage suffered serious injury or death when compared those without helmets. One would expect the helmeted riders would have a reduced percentage of serious injury or death.

Can this be explained by risk compensation or demographics?

Nonetheless, the OSHP apparently didn’t do much analysis since they’ve cut-and-pasted a quote that’s unsupported by their own data: “Making the use of helmets the single most effective countermeasure available to reduce head injuries and fatalities resulting from bicycle crashes.”

And just to be sure that 2007 wasn’t simply a unique year, we looked at this data back to 2004. For every year, bicyclists wearing helmets in crashes suffered an equal or greater percentage of serious injury or death.

For what it’s worth, there is not a trend towards increased helmet use among those involved in reported bicyclist accidents within Michigan.

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7 Responses to “Pedestrian and bicycle safety data analysis”

  1. Streetsblog New York City » Today’s Headlines Says:

    [...] Planners Study Car-Deer Crashes More Than Car-Ped Crashes (M-Bike via Streetsblog.net) More headlines at Streetsblog Capitol [...]

  2. Streetsblog Los Angeles » Today’s Headlines Says:

    [...] Planners Study Car-Deer Crashes More Than Car-Ped Crashes (M-Bike via Streetsblog.net) More headlines at Streetsblog Capitol [...]

  3. Stuff I found while surfing the web « Witch on a Bicycle Says:

    [...] on another blog where he actually looks at the data instead of just reading the words alongside. Pedestrian and bicycle safety data analysis Egads if people were to actually read the data, they might have to get real jobs! Of course being a [...]

  4. Joel Batterman Says:

    Thanks for this. The appalling state of pedestrian and bicycle safety, or lack thereof, in the City of Detroit is a clear-cut environmental justice issue.

    There’s a sentence in the generally commendable MI Pedestrian and Bicycle Safety Action Plan that strikes me as odd. “The need to reduce pedestrian/bicyclist deaths and injuries, *even in the face of ongoing efforts to increase levels of walking and bicycling,* continues to be an important goal…” Wait a minute–isn’t making walking and biking safer a critical component, indeed perhaps *the* critical component, of efforts to increase levels of walking and bicycling? The goals of decreased crashes and increased walking and bicycling aren’t in opposition!

    That should be a matter of common sense, but (as usual) Portland, OR has the data to prove it. From 1991 to 2005, bicycle traffic in Portland more than quadrupled, while the number of bike crashes remained flat–representing a dramatic decline in crash rates. Pedestrian injuries declined dramatically as well, and, significantly, so did injuries to motorists. What’s safer for bicyclists and pedestrians (especially slower motor vehicle speeds) is also safer for drivers.

    See slides 4, 5, and 7 in Portland’s 2007 annual transportation report: http://www.portlandonline.com/transportation/index.cfm?c=44721&a=215540. For further reading, slides 13, 14 and 16 of the city’s 2008 report include some truly astonishing charts: http://www.portlandonline.com/transportation/index.cfm?c=44721&a=214956

    Michiganders must press for far more aggressive action to ensure the safety of all modes of transportation.

  5. Keeping bad drivers off the roads « BikingInLA Says:

    [...] have done to avoid it. A Detroit writer analyzes the official crash analysis, and find that both cycling and pedestrian deaths were under reported. Finally, a cyclist from Down Under documents his daily commute; clearly, they [...]

  6. Hannah Says:

    You note “that it is unreported whether helmets were worn in a little over half of the crashes.”

    Can you give the breakdown of the injury vs. non-injury crashes where helmet use wasn’t reported? I’m having a little trouble with your statistics and maybe having all the data in the table would be helpful. Should this read that 18% of riders wearing helmets in crashes were seriously injured or killed and 46% had minor or no injuries? What about the other 36% of riders who were in a crash and wore a helmet?

    I really appreciate you actually looking at the numbers since it seems nobody else is, but having the percentages in the table add up to 100% would be helpful. Thanks!

  7. Streetsblog New York City » The Weekly Carnage Says:

    [...] Detroit, MI: Planners Study Deer-Involved Crashes More Than Bike-Ped Deaths (M-Bike) [...]

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