Speed-securing measures on rural roads in Sweden: An observational study

Speed-securing measures are intended to, as the name suggests, to secure that the speeds of road users do not exceed the safe speed for a given type of environment. The purpose of this study was to make an evaluation of existing speed-securing measures on rural roads in Sweden to see how well they manage to limit the speed. A total of 34 unique locations have been filmed with drones with varying speed limits between 40 and 70 km/h. The analysis focused on the radius of both the individual vehicle trajectories and the radius of the roads themselves and how they relate to the speed choice of the drivers (including the 85th percentile speed). The result shows a moderate correlation between both types of radii and the speed choice of the drivers. In addition, the result also shows only a weak correlation between the driven radius and the radius of the roads themselves. Finally, the result also shows that only 17 locations manage to keep the 85th percentile speeds under the speed limit. Overall, the study suggests that the radius of the infrastructure is an important factor to lower the speed but the lack of a clear relationship between the driven radius and the radius of the road shows that more research is needed to properly understand why some locations work better than others.