The best views of Washington are undoubtedly from above, on flights to and from National Airport.
When I saw the aerial photo taken by Dan Macy, I knew I had to use it as the background for a map. Visit the Birds-eye view of CaBi stations app and see if you enjoy the view as much as I do.
The map does more than just map Capital Bikeshare stations. You can study stats culled from trip history records accumulated through 2013. In the image above, stations are colored according to how many bikeouts they had in the past year. The median number is 2,324, so stations with more are shown in red, and those with less are shown in blue. A slider lets you adjust which number to use as a threshold, so you can easily identify the most-popular stations. Dupont Circle and Columbus Circle stand out as the top stations.
You can also study which stations are more popular with subscribers and casual members. The view above draws stations in green if 50 percent or more of the bikeouts are from subscribers. Not surprising that most stations are green, since overall, 80 percent of bikeouts are from subscribers. You can adjust the threshold to see the most polarized stations. It’s clear that casual riders (those with the shorter 1- or 3-day memberships) dominate the CaBi stations near the Mall.
People who study bikesharing systems love looking at imbalance stats, so I came up with two formulas for displaying an imbalance rating. The “signed” formula shows a positive percentage for stations that have more bikeouts than bikeins, and a negative percentage for the reverse. In the photo above, purple stations have more bikeouts than bikeins, and yellow stations have more more bikeins than bikeouts.
The “unsigned” version of the formula is just the absolute value of the other formula. So now, the percentage disregards whether there’s an imbalance of bikeouts or bikeins. You can adjust the slider to discover the most unbalanced stations. It turns out that the median level of imbalancedness is 12 percent, meaning half of the stations are more balanced. My formula is the difference between bikeouts and bikeins, divided by whichever number is larger.
There’re two more views you can select that don’t come from the 2013 stats. This first one shows when each station came into operation. By adjusting the slider, you can see how the CaBi system has grown since opening in 2010.
One thing these photos show is how flat Washington is, which makes it great for cycling. But even so, there is some variation in elevation, which you can explore in the final view. The stations range from a low of 1.3 meters (or 4.3 feet) above sea level at Prince St & Union St in Alexandria, to a high of 146.3 meters (480 feet) at King Farm Blvd & Piccard Dr in Rockville.
Unfortunately, the aerial photo doesn’t allow us to view all of the 309 stations we have data for, such as the new stations in Rockville.
I have a bit more information about the code on my blog. Mapping to a photo isn’t as accurate or as flexible as using a regular map, but there’s something compelling about using a view of our city as seen from someone in an actual plane. And hopefully this little experiment helps people better understand Capital Bikeshare’s place in the fabric of our region.