Citi Bike has had immense success in building a large base of New York City riders in a very short time. However, while Alta Bicycle Share (the company that owns the company that operates Citi Bike) was surprised by their success in attracting annual subscribers, they had anticipated more revenue from daily and weekly riders. Attracting these short-term customers is important to Citi Bike’s success. Consider:

Short-term riders pay more per ride than annual subscribers.

Short-term riders are more likely to pay fees for exceeding their time limits.

Short-term riders provide infusions of cash between peak re-subscription periods.

Many subscribers use Citi Bike for their daily commute (especially to and from train stations), and many short-term customers are from out of town. For this reason, I will call them commuters and tourists. Just be aware that this is an over-simplification – in reality, residents may purchase short-term passes, and subscribers may not use Citi Bike to commute.

Here’s a look at Citi Bike use over the first 8 months for which data is available:

Do tourists use Citi Bikes differently than commuters? Here’s a comparison of how far they go:

Basically, tourists exhibit slightly more variance than commuters (likely due to unfamiliarity with the city/system), and on average dock slightly farther away.

Now let’s compare how long they keep the bikes out. This is especially important, as regular commuters pay extra fees after 45 minutes, while short-term visitors get only 30 minutes:

Commuters are quite skilled at re-docking their bicycles within the 45-minute allotment, whereas tourists are skilled at exceeding their 30-minute allotment (and exceeding 45 minutes, too).

One strange thing about Citi Bike’s business model is that riders take inventory from wherever they want (within the system) and leave it wherever they want. This inevitably leads to bikes disappearing from where they are wanted, and reappearing in the limited number of docking stations where riders want to stop. Citi Bike has responded to these problems with bike trucks that circulate and relocate bikes to where they are in demand.

I took a look at some of these imbalances, and experimented with ways to analyze and visualize bike rentals and returns at given stations. A look at bikes being taken vs. bikes being docked at each station within a short time frame illustrates the imbalances that occur:

In reality, within 8 months of operation, many stations with less than 60 total docks had accumulated net imbalances of several 1000’s.

The following image represents bike imbalances from July 2013 through February 2014 with two overlapping circles for each bike station – one for commuters (left), and one for tourists (right):

For example, in the image above, the green swath on Broadway below Central Park (coming down from top center) indicates an area from which riders take bikes and go more often than they stop and dock.

Imbalances like the ones shown above frustrate Citi Bike riders and can dissuade potential customers. Finding no available bikes may lead to a quick change in plans, and finding no available docks may lead to frustration and bad word-of-mouth. New York City has a virtually endless supply of tourists who might want to try riding a Citi Bike, but people unfamiliar with the city and the bike system may be easily put off by inconvenience and confusion.

The following graphs show average hourly going (green graphs, top row) and stopping (red graphs, 2nd row) for each day of the week (Monday-Sunday) in July and August, for all stations. Within each graph, commuters are on the left (mostly darker shades) and tourists are on the right (mostly lighter):

The main takeaway from the above is the clear commuting pattern indicated by the dark bars on the left side of the Monday-Friday graphs. That includes all annual subscribers, and somewhat validates the idea of calling them commuters. Commuter bike use peaks at around 8-9 am weekday mornings and 6-7 pm weekday evenings. The number of tourists is relatively slight during the week – especially in the morning. Apparently non-commuters like to sleep in.

On weekends, many more tourists ride Citi Bikes, and peak riding times for both groups last from early afternoon into the evening.

Let’s set the commuters aside and focus on tourists for the next pair of images:

As shown above on the right, a small number of stations get vastly more tourists than the others. To the left are relative imbalances in both directions, but in reality the most popular destinations (in red) have much larger imbalances than the points of departure (in green). The implication is that tourists may take bikes from wherever they are, but often have similar destinations in mind.

As shown above, the greatest geographic concentration of tourists on Citi Bikes is by Central Park. The image below shows tourists’ hourly use of the four Central Park stations in summer (July and August). In essence, lots of tourists take Citi Bikes to Central Park on summer weekends:

Unsurprisingly, summer use by daily and weekly riders peaks over the weekend, with a slight uptick on Friday afternoons, and a much greater increase on Saturdays and Sundays.

Looking again at bike going and stopping, but honing in on just the four Central Park stations, we see that commuting lessens and short-term use increases (especially on weekends):

We can see above in green that subscribers are much more likely to take bicycles from Central Park stations in the evening. They could be taking rides in the park, but it’s very likely they’re just having trouble finding bicycles available on Broadway.

Here’s a look at the bike imbalances created by this pattern of use on Saturdays and Sundays by Central Park:

As depicted above, weekend afternoons in Central Park have a whole lot of docking going on. Interestingly, commuters are not really exacerbating the problem, but they’re also not symbiotically resolving it by riding bikes away as tourists fill the empty docks.

On summer Saturday afternoons, bike arrivals in Central Park pick up around 11 am, and on average over 50 docks are filled in the next few hours. On Sundays, the imbalance is even worse, with bikes starting to arrive in the morning, and more than 60 docks filled by late afternoon.

These imbalances suggest that for peak tourist weekends, Citi Bike may want to move bikes away from the Central Park stations, and situate them across the broader network of stations from which tourists embark. This could potentially lead to better service using existing resources.

This is just one set of examples of using visualizations to investigate and represent data. Are there other graphs you’d like to see here?