California bicycle crashes 2012

I began geocoding bike and bicycle related ‘incidents’ reported to the California Highway Patrol dispatch centers last May. Here’s what they look like on a map.

California crashes 2012

My mapping software needs some work, but you can look at the May – December data on this map. Zoom into your neighborhood to see where the hot spots are.

I only record incidents that are reported to CHP dispatch centers. About 70% of 911 calls made via cell phone go through the CHP, but about 300 local departments in California field their own 911 calls made from mobile devices. That’s why you’ll see some interesting empty zones such as San Francisco and Davis, both of which have high levels of bicycling and a correspondingly high number of bicycle crashes, but little to nothing recorded on my map.

Note also the numerous false positives. I match on “bike” (among other search terms) in my automated collection of data, which means I’ll catch a number of motorcycle crashes as well as the occasional “power pole in bike lane” report. I filter out “road hazard” reports.

I think this map mostly shows where people are riding their bicycles, and you can zoom in to various areas to see where crashes are in your local area. There’s one instance I know of that involved somebody I know personally.

You can ignore the red dots outside of California — those are geocoding errors because I don’t bound searches to inside of California. For ambiguous locations, Google guesses the country, and sometimes guesses wrong. Fixing the code to limit searches to inside of California is on my TODO list.

Click here to view my California bicycle crash map. You can also view my three year record of CHP bicycle dispatches in text format here if you’re so inclined. You can see, for example, that 17% of reported crashes in December are hit and run.


  1. This is important work, mapping bicycle accident allows all interested parties to better understand the need for safety improvements and also undeline the need for educating motorists and cyclists of the severity of the outcome when a motor vehicle collides with a bicycle.

  2. I think it’d be pretty awesome if you could augment the web map application where you can toggle the display of accidents by date and maybe tabulate the data. Just a thought.


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