Infomap or Cartographic? My Take on Mapping Toronto’s Traffic Lights

April 4th, 2014 by Claus Rinner

Toronto writer/blogger Chris Bateman recently publicized a beautiful white-on-black map of all Toronto traffic lights, which was created by our very own Master of Spatial Analysis (MSA) student William Davis. Chris’ brief yet insightful post on blogTO can be found at http://www.blogto.com/city/2014/03/a_map_of_every_traffic_signal_in_toronto/. Inspired by William’s idea and the creative map designs by several MSA students in my cartography course in the fall semester, I thought I’d give the traffic lights map a try. Another trigger for my experiment was a comment from blogTO reader “Red Menace” about the traffic lights, complaining that “Most of them are red too.” Here is how I proceeded:

  1. Visit the City of Toronto’s open data catalogue, click on “GET THE DATA”, and find “Traffic Signals Tabular”. I would love to provide a direct link, but they changed URLs to include some lengthy session IDs, which I cannot post here – currently, http://toronto.ca/open still works as an entry point.
  2. Download “All traffic signals – CSV”, “Traffic signals with APS – CSV”, and “Pedestrian crossovers – CSV”. According to the readme file, APS refers to “active traffic signal enabled with sound (Accessible Pedestrian Signals)”. CSV is a tabular file format (Comma-Separated Values).
  3. Start the open-source geographic information system QGIS 2.2. In the Layer menu, use “Add Delimited Text Layer…” to open each of the three CSV files, discarding the first line and assigning the Longitude and Latitude fields to the x and y coordinates respectively.
  4. Upon preliminary display, change the coordinate reference system of the QGIS project to UTM Zone 17N and display all traffic signals as red dots, pedestrian crossovers as yellow dots, and sound-enabled signals as green dots.
  5. In QGIS’ print composer, add new map, rotate by +18 degrees, set background to black, and fiddle with map extent and scale until everything fits. Then export as image, et voila!

traffic_signals_10p

Click image to open larger version.
Contains information licensed under the Open Government Licence – Toronto. 

With red dots representing “normal” traffic lights, green dots overlaying those lights that are friendly to visually impaired pedestrians, and yellow dots showing the locations of mid-block crosswalks, my map focuses a bit more on conveying thematic information than on a fashionable graphic design. While I am afraid that design gurus (in particular our trend-setting students!) may sniff at it, I like to think of it as an “infomap” or “cartographic” (read: carto-graphic), analogous to the now ubiquitous “infographic”.

Update 10 April 2014: I want to share another version, in which I created a halo around the red and yellow dots by defining a semi-transparent, 1mm wide outline of the same colour.

traffic_signals_halos_zoom

Click image to open full version.
Contains information licensed under the Open Government Licence – Toronto.

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