13 bicycle crashes times two

While looking at the California Bicycle Crash Map last night I noticed something interesting: Although Southern California has twice the population of Northern California, the same number of bike crashes — thirteen — are reported to the California Highway Patrol for each region.

Here’s the chunk of Southern California I looked at, centering on Los Angeles and Orange County. There are 13 of those red and yellow circles on this map. About 16 million people live here.

13 bike crashes in Southern California

Now let’s look at a part of Northern California centered on the San Francisco Bay Area, where about 8 million people live. The map zoom level is identical, but we have the same number of bike crashes with half the population.

13 bike crashes in Northern California

I cropped Sacramento out of the Norcal picture. If we leave that in we add another million people and four more bike crashes for the period from May 25 2012 to May 30 2012.

Does this mean The Southland is safer for cyclists than the San Francisco Bay Area? Or do we have twice as many cyclists per population around here?

Or is the dataset of just five days worth of crashes just too small to gather any kind of statistical meaning? I’ll revisit this in another month and we’ll see what happens. In the meantime, please don’t become a statistic.

You can view the California bicycle crash map here. Red are crashes reported to the CHP before “today.” Yellow circles mark crashes that occurred today. The map is updated in real time (within about 10 minutes of a report), so you can see what happens on an hourly basis, if you’d like.


  1. I think it has more to do with a larger area served by the CHP in NorCal, whereas in SoCal, most bike collisions occur within cities served by local police, with the calls routed through local 911 systems. 

    Now, if you can figure out a way to capture bike incidents handled by local authorities…

  2. I think that could be part of it too. I thought CHP handled all 911 calls from cell phones, but I just learned that’s not necessarily the case in SoCal. The Orange County Sheriffs office, for example, says they handle all mobile calls originating from towers in that area. LA County calls, though, look like they go through CHP.

    EDIT: I dug some more, and it appears some cities in Los Angeles take cell phone 911 calls directly. Los Angeles and Long Beach, and maybe most of the others too. The details are more difficult to find than I expected. San Francisco also handles some cell phone 911 calls directly, depending on tower proximity to freeways.

    Regarding local calls — I was looking to see what data might be available from the 911 regional dispatch center for Santa Cruz County. Alas, nothing seems to be there in real time.

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