How sustainable is route navigation? A comparison between commercial route planners and the policy principles of road categorizations

In-Vehicle route planning is used to support a driver’s route choice and to guide a driver to his/her destination. . However, the suggested route takes less account of environmental aspects, which also could lead to cut-through traffic. Nonetheless, route-guiding systems may provide opportunities to stimulate a sustainable usage of the road network wherefore an integration of route planning and measures to improve traffic livability and safety is essential. The Flanders Spatial Structure plan describes certain categories of roads for the optimization of the road network based on selectively prioritizing either accessibility or livability. The aim of this paper is to examine to what extent route planners apply the principles of this (policy-made) road categorization while calculating a proposed route. To achieve this, relevant origins and destination are selected in the study area south-east of Antwerp. Several route planners are used to calculate routes between each origin/destination relation. Between each origin and destination occurs a ‘desired’ route which follows the principles of the Flanders Spatial Structure plan. The routes suggested by route planners are then compared with the corresponding desired route, after which the road classification usage of route planners can be evaluated. This paper will describe the in-depth analysis of this research. First results of the research show that different route planners may suggest different routes. These routes can also differ from the desired route based on the Flemish Spatial Structure plan. By comparing planned routes with the corresponding desired routes, differences in road usage are apparent. These deviations are mostly found in the use of low and/or high categorized roads. Especially roads of the lowest category - which should only be used to give access to adjacent parcels - are frequently used by route planners to guide through-traffic without considering the lower function of these roads. For some of these suggested routes, the desired route is a feasible alternative. The desired routes do not necessarily deviate from suggested routes in the matter of time or distance, but will prevent the use of local roads for through-traffic. It is concluded that the implementation of the Flemish road categorization in routing algorithms has the potential to stimulate more sustainable driving behavior with more sustainable route choices.