The Fremont Bridge is a drawbridge in Seattle, Washington with clearly allocated bike lanes. The City of Seattle built a set of traffic counters in both the north- and southbound lanes. The output data from these sensors uploads to data.seattle.gov.
This visualization was built in D3 and derived from mbostock's calendar view d3 block, in turn inspired by Rick Wicklin and Allison's 2009 Data Expo submission. Dark squares indicate days of heavy bike traffic on the bridge, and light blue squares indicate light traffic. White squares with no outline indicate periods for which there are no data (before October, 2012, or current/future months). The calendar view graph will update monthly to include the previous month's traffic, thanks to data.seattle.gov's API.
All data copyright City of Seattle. Background image courtesy of Ryan McGuire and Gratisography. Special thanks to Kevin Hu and Nick Stepro for their help in this exercise.