Where in the world are the straightest roads and where are the curviest? Rory McCann used OpenStreetMap data to find out. After extracting street data from the crowdsourced mapping project using Osmosis, McCann then used a python script that he developed to determine the “bendiness” of each road segment, which he defines as “the length of the road divided by the straight line difference between it’s end points”. Therefore a perfectly straight road would have a ratio of 1:1. The curvier the road, the higher the ratio of actual road length to the straight line distance between the beginning of the road segment to the end of the road segment.
McCann proposed the idea that roads developed in the age of the automobile would be straighter than roads developed prior to the past hundred years:
One theory I had was that Europe, where current roads are based on older roads that predate cars, would have more bends and curves than the USA, where current roads were (in many places) only put in in the last 150 → 100 years, and probably put in directly and dead straight.
Indeed, McCann’s spatial analysis revealed that the Midwest in the United States and the plains of Canada had significantly more roads that were straight compared to Europe. In Europe, the Netherlands stood out as the country with the straightest roads. In the screenshot below, red reflects the straightest roads and blue the curviest.
Read McCann’s post about his bendy road mapping to learn more about how he pulled the data, analyzed the results, and mapped it all out. He also included a section describing the open source tool he used such as QGIS, Leaflet, and TileMill. McCann also discusses some of the shortcomings of the project. For those that want to play around with the code, McCann has posted it here: openstreetmap-bendy-roads.