Safest day to cycle?
Here’s a count of all cycling fatalities in California from 2001 to 2012, tabulated by year and day of week. The raw data comes from SWITRS.
Is there any knowledge to be gleaned here about the safest day to cycle? One of the biggest problems in analyzing SWITRS cycling data comes from the lack of base rates, or overall counts of cyclists for a given period. The single worst day came from the 34 people who died on Sundays in 2004, but without knowing whether many people were cycling on Sundays in 2004, we can’t determine the rate of fatalities, and there’s not much we can derive about safety from these numbers. In a word, then, we don’t know when it’s safest to ride.
Still, my guess is that cycling rates climb on the weekends. If that’s true, we should expect to see higher fatalities overall on Saturdays and Sundays. They don’t show here in the totals for the weekends, which look rather like the rest of the week. The cause could be as simple as less car traffic on the weekends, or as rich and complex as this notion of safety in numbers, the idea that so many people are cycling on the weekends that drivers notice them.
Ultimately, we really need better information about cycling in California. We don’t know much about ourselves, how many of us ride, when we do, how we get into crashes, and why.