Monday, May 05, 2014

Twitter, ADD, and that UC study

Photo, Centers for Disease Control

Maybe it's because of a Twitter-based intellectual degeneration, but I get some remarkably stupid comments on that important UC study of the city's radically flawed method of counting cycling accidents. A good recent example:

Regarding the UC study - How about you get someone who isn't freaked out by bicycles to explain what the study might mean? All it tells me is that people (not specific on age, what they were doing) can get hurt biking, like they can with all kinds of other activities. Do you honestly believe that people think biking is absolutely safe?

That I'm "freaked out by bikes" or anti-bike has been a routine charge by the remedial readers in the bike movement. Actually, I became interested in the issue when City Hall was rushing its 500-page Bicycle Plan through the process without any environmental review that was clearly required by the California Environmental Quality Act (CEQA). 

I also noted that bike advocates were consistently downplaying the dangers in riding bikes to encourage more people---even children---to ride bikes in San Francisco. 

This is an important public policy issue, since the Bicycle Plan is taking away dozens of traffic lanes and thousands of parking spaces from busy city streets to make bike lanes for a small minority of cyclists (After years of pro-bike, anti-car propaganda from City Hall and the Bicycle Coalition, only 3.4% of all trips in the city are by bicycle).

A short recap for those---there are so many!---with attention deficit disorder who can't focus long enough to read even short documents: San Francisco has long relied on police reports to count injury accidents. Based largely on those police reports, every year the MTA publishes a count of vehicle, pedestrian, and cycling accidents in its Collisions Report (see page 3 for the count methodology).

The UC study was done by University of California doctors. The New York Times did a story (How Safe Is Cycling? It’s Hard to Sayin October, 2013 that referred to the study:

Dr. Rochelle Dicker, a trauma surgeon at the University of California, San Francisco, does not see it that way. She cares for victims of the worst bicycle injuries, people who might need surgery and often end up in intensive care. So she decided to investigate those crashes. She and her colleagues reviewed hospital and police records for 2,504 bicyclists who had been treated at San Francisco General Hospital. 

She expected that most of these serious injuries would involve cars; to her surprise, nearly half did not. She suspects that many cyclists with severe injuries were swerving to avoid a pedestrian or got their bike wheels caught in light-rail tracks, for example. Cyclists wounded in crashes that did not involve a car were more than four times as likely to be hurt so badly that they were admitted to the hospital. Yet these injuries often did not result in police reports---a frequent source of injury data---and appeared only in the hospital trauma registry. Dr. Dicker is not a cyclist, but she said, “Lots of my colleagues do not want to ride after seeing these injuries.”

Half of 2,504 would be 1,252 cycling accidents not counted by the city between 2000 and 2009, the period covered by the study.

From the abstract of the UC study:

Police reports are the industry standard for assessing transportation-related collisions and informing policies and interventions that address the issue. Previous studies have suggested that police reports miss a substantial portion of bicycle crashes not involving motor vehicles. No study to date has explored the health and economic impact of cyclist-only (CO) injuries for adults in the United States. Our objective was to use trauma registry data to investigate possible under-representation of certain cyclist injuries and characterize cost...

Of all bicycle-related injuries at SFGH[San Francisco General Hospital], 41.5% were CO[cyclist-only] injuries and 58.5% were AVB[auto-versus-bicycle] injuries. Those with CO injuries were more than four times as likely to be required of hospital admission compared with those with AVB injuries...From 2000 to 2009, 54.5% of bicycle injuries treated at SFGH were not associated with a police report, revealing that bicycle crashes and injuries are under-recognized in San Francisco.

Since the text of the study is behind a paywall, I transcribed it here.

Neither the Chronicle, the Examiner, nor either of the city's weeklies have even mentioned the study yet. This is apparently because its findings undermine the groupthink acceptance by the local media of City Hall's anti-car, pro-bike policies that are now redesigning city streets on behalf of a small special interest group against the interests of more than 95% of those who now use city streets, including Muni passengers.

I'm hardly the only one to notice the dangers of riding a bike in San Francisco---or anywhere, for that matter. From the Centers for Disease Control and Prevention [Later: the CDC has removed from this link both the picture above and the paragraph below. I asked them for an explanation some time ago but they didn't respond]:

While only 1% of all trips taken in the U.S. are by bicycle, bicyclists face a higher risk of crash-related injury and deaths than occupants of motor vehicles do. In 2010 in the U.S., almost 800 bicyclists were killed and there were an estimated 515,000 emergency department visits due to bicycle-related injuries. Data from 2005 show fatal and non-fatal crash-related injuries to bicyclists resulted in lifetime medical costs and productivity losses of $5 billion.

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