What Public Transit API Logs Tell Us about Travel Flows

In the field of smart cities, researchers need an indication of how people move in and between cities. Yet, getting statistics of travel flows within public transit systems has proven to be troublesome. In order to get an indication of public transit travel flows in Belgium, we analyzed the query logs of the iRail API, a highly expressive route planning API for the Belgian railways. We were able to study similar to 100k to 500k requests for each month between October 2012 and November 2015, which is between 0.56% and 1.66% of the amount of monthly passengers. Using data visualizations, we illustrate the commuting patterns in Belgium and confirm that Brussels, the capital, acts as a central hub. The Flemish region appears to be polycentric, while in the Walloon region, everything converges on Brussels. The findings correspond to the real travel demand, according to experts of the passenger federation Trein Tram Bus. We conclude that query logs of route planners are of high importance in getting an indication of travel flows. However, better travel intentions would be acquirable using dedicated HTTP POST requests.