Implementing a chord diagram in D3

This final visualization is more complicated on both the data and coding fronts. The visualization is based on data released several years ago as part of the Hubway Data Visualization Challenges (http://hubwaydatachallenge.org/). It's a large dataset that represents every trip, including departure and arrival stations, on Boston's Hubway bike-share program (now called Blue Bikes). This visualization shows the relationship between the top ten most popular stations, illustrating the number of trips that happened between stations in the top ten. This is interesting to see which of the major hubs are illustrating potential holes in the public transportation network (lots of people are taking trips between transit hubs like North Station and South Station) or are potentially being used by tourists to see the sights in Boston (many South Station trips return back to South Station).  

The final visualization looks like this. Each arc represents a departure station...