The C is for Crank

Is Bike Ridership Really Down?

By Erica C. Barnett October 20, 2011

Is bike ridership really down? Over at the PI.com, Scott Gutierrez has a story---headlined, "Numbers show bike traffic fell throughout Seattle"---that certainly implies it is.

"A city-sponsored count of bicyclists on Seattle streets last year showed bike traffic fell during Mayor Mike McGinn's second year in office," Gutierrez writes. "The one-day 2010 annual bike count showed mixed results, with bike use increasing Downtown but falling 15 percent everywhere else in the city." This, the story concludes, suggests that Mayor McGinn's Walk Bike Ride effort---a campaign to get more people using transit, walking, and biking to work---has had "mixed results."[pullquote]But there are numerous problems with those stats, and with PI's conclusion.[/pullquote]

But there are numerous problems with those stats, and with that conclusion. First, the numbers represent only a single, one-day annual count, rather than the four-times-a-year count bike experts say is ideal (and that's being implemented in other cities). That count can be skewed by factors that change from day to day, like whether it's raining.

Second, a two-year comparison doesn't show trends over time. The difference between two data points is basically meaningless; the real question is, how has bike ridership been trending? In Seattle's case, ridership has been going up steadily for the past decade. One year of slight decline does not lead to the conclusion "bike traffic fell throughout Seattle."

Finally, there's those pesky actual numbers. Considered in isolation, the number of cyclists counted outside downtown did indeed decline---from 4,666 in 2008, the last year for which data is available, to 3,981 in 2010. But wait. The number of cyclists counted downtown actually rose---from 2,677 in 2009 to 3,251 in 2010. The story acknowledges this, but doesn't add those numbers up. Taken together, the number of cyclists counted citywide only decreased by 111---an overall decline of just 1.5 percent. That doesn't make as good of a headline as "bike traffic fell throughout Seattle," but it's more accurate---and more honest.

The city will release more traffic data from 2010 tomorrow; I'll have a full report tomorrow afternoon.
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