This interactive bubble map lets you study travel patterns, showing results from the 2007 Survey of Metro Passenger Origin and Destination Stations. The survey got results from 708,406 passengers, asking them their origin and destination. I obtained a spreadsheet of the responses, but it’s hard to analyze a table of numbers with 86 rows and 86 columns. So, I decided to create a map using bubbles to reflect the volume of traffic. Yes, the data is five years old, but it’s all I had available.

When you move your cursor over a station, red bubbles appear over the other stations, their size reflecting the number of trips that originated at those stations that ended at the one you selected. An option at the bottom lets you see the reverse: trips from your selection to each of the remaining stations (using orange bubbles). You can also select a station via the menu at the bottom. Your chosen station is given a blue bubble showing the total. To view the exact numbers, click the “list” button. Your screen may not be tall enough to view all entries. (Hit the enter key to continue.)

To implement this, I first investigated Google Fusion Tables, but grew frustrated with the limited interface in their beta release. I found greater success with the Google Maps JavaScript API V3, which I have already used on other projects.

Showing Metro Trips with a Bubble Map

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