Plain Version. See below for explanation. tl;dr: Size = activity = outgoing + incoming. Color = flux = outgoing – incoming. Red means more people arriving, green means more people leaving. All numbers are per day that the station was open, for the time range displayed by slider. For other tech details, see the related blog post, or see the source on GitHub.
This plot displays the average number of trips taken in the time window, for whichever weekdays are selected. If you want to look at weekday activity only, uncheck Saturday and Sunday (the buttons toggle all relevant checkboxes to make it easier to examine only weekdays or weekends). Note that some stations have been open longer than others and they close at different times for the winter; for that reason we divided by the total number of days each year the station was open to get a fair picture.
The size of each marker represents the total number of outgoing + total number of incoming trips, which I dubbed “activity”. So if 5 people arrived at a station and 4 people left, the activity would be 9 (scaled in an arbitrary way for plotting purposes).
The saturation of each marker represents difference between outgoing and incoming, which I dubbed “flux”. So in the example above we’d have a flux of 5-4 = 1. I used green for positive and red for negative, just to make it easy to tell the difference. There are sliders to adjust the scaling of the size and color to taste (under “View Options”).
So if a bubble is large and white it means a lot of people are coming and going, in roughly equal amounts. If it were large and deep red it means a lot of people were arriving, large and deep green would be a lot of people arriving.
You can see the numbers by mousing over a station. Clicking on a station shows them in a permanent info window, and also draws paths representing the most common trips taken leaving from and arriving to that station. It also displays a graph below the map, showing the total activity for that station over the course of a day. That’s basically the
“activity” number that one would get if they moved the slider from morning to night.
The bike path overlay is turned on by default, turning it off shows the standard Google Maps road map. There is also an overlay which shows the population density of the area in question (by census tract). This is turned off by default, it can be toggled with a check box.
Population data from the 2010 census
; Massachusetts has state code 25.
Map created and stations using the Google Maps API.