Capital Bikeshare: Usage and Weather

Next in a series of posts mining crowd-sourced Capital Bikeshare data. This one does a simple correlation between temperature and usage. If you’re really bored, see also parts 1, 2, 3, 4, 5, 6,7, and 8.

How much does the weather matter in Capital Bikeshare customers’ decisions to hop on a big red bike?  Here’s a quick overlay of Bikeshare usage vs. daily temperatures recorded at National Airport, via WeatherSource.  That’s all I could easily get my hands on.  (Anyone have temperature and precipitation, by day or hour, for all of 2011?)

First, here’s a quick look Bikeshare usage and daily mean temperature recorded at National Airport, in 2011. Since Bikeshare use is concentrated in the daylight hours it makes sense to use something higher than the mean temperature, but hey.  Keep in mind, as always , that the system expanded,  in both users/trips/demand, as well as stations/bikes/supply over the same time period, so we’re also watching system growth over the course of the year.

Bikeshare usage vs. average temperatures in 2011 (click for larger)

A few observations from this:

• Take early 2011 with a grain of salt; the system was still taking hold at that point.
• During a few weeks of uncomfortable heat in the July last year, usage dropped off. Makes sense to me – it was really sticky there for awhile.
• What’s going on with the very low usage outlier days in the shoulder seasons? Precipitation? Special events? (Need precipitation data)
• If you discount the spring, usage tends to track pretty well with temperatures.

But let’s look at this just along the dimensions of usage and temperature, regardless of seasonal effects. This time, I’ll look at high temperature, rather than mean temperature. I picked a polynomial line of best fit that seemed right to me:

Average high temperature vs. Bikeshare usage in 2011. Each dot = one day in 2011.

• It’s interesting that the data are very tightly clustered at the right and left of this graph, but more scattershot in the middle temperatures.  In other words, when it dips below 40 and above the mid 80s, Bikeshare use is pretty easy to predict using temperature.  In the middle (say, 50s through 70s), temperature is less a driving force in peoples’ decisions to bike.
• Low temperatures (below 40s) tend to discourage use significantly; very high temperatures do too equally consistently, but ridership is still higher in summer heat.
• But, the pattern is far less temperature-driven in the middle range. My guess is that precipitation , humidity and “feel” of the weather may have more to do with people’s decision to bike in the shoulder seasons.  As a year-round bike commuter I know firsthand that a day that will eventually get into the 60s and 70s can start out feeling pretty raw in the morning.

There’s probably alot more to be learned here from ridership vs. weather, and this just begins to scratch the surface. Anyone else want to give it a whirl? Got better weather data to play with? Let me know!

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