At Critical Mass events large numbers of cyclists meet and drive through the city in a random way as a convoy. This serves to create awareness for cycling as a mode of transport.

I logged the route of the november Critical Mass in Essen and turned it into an animated map. The background shows the route network available to cyclists, i.e. the road network including cycling tracks but without footpaths and motorways.

(Note: the animation may take a moment to load.)

Looking at the map shows some interesting behavioral trends that are not immediately apparent when driving in the convoy. There seems to be a preference for wide main roads. The reason is that these are better suited when cycling in large numbers and are better for getting visibily and creating some chaos. An alternation can be seen between cycling to somewhere and cycling in a random fashion. The route to the south and back connects the Essen city center and the southern subcenter in Rüttenscheidt. During random tours there seems to be a preference for right turns resulting in clockwise movements.

For those interested, here some details about how this animation was made. It was constructed using the open source tools QGIS with the Time Manager plugin, Gimp, and the open source GPSLogger app. The background shows Open Streetmap data. Only those roads are displayed that are usable by cyclists i.e. normal roads and cycling tracks, but not foot paths and motorways.

First I logged the tour at a 10 second interval using the app. The resulting CSV file I imported into QGIS. I converted the file format to Geojson which allows editing. I manually corrected the jitters in the logged data which showed some deviations of 10-20 meters. Then I exported the file format to GML because the Time Manager does not seem to support all functions for geojson files. I set up the time animation in the Time Manager Plugin using an interpolation for the points. The glow effect was created with the drawing effect „outer glow“. The trail in the animation was created by registering the points again, setting the end time to cumulative and showing only the glow without the source. The resulting time animation I exported as individual frames. These I loaded as layers in Gimp. I rescaled the image and applied the gif optimization filter. I added the title and finally exported the animation as a gif.