Repeated measurements of lateral position and speed at horizontal curves on very low-volume rural road

Speed and lateral position are recognized as influential factors in the occurrence of road crashes at curves on two-lane rural roads. Studying the driver behavior at those road sections can help in preventing accidents by choosing the adequate countermeasures. However, driver behavior can be substantially non-uniform on very low-volume rural roads since the free-flow condition occurs. On the other hand, some literature studies affirm that road familiarity can be influential on driving behavior, by reporting changes due to the acquired familiarity with the road environment. An on-road test was planned on a very low-volume two lane rural road in the District of Bari in Puglia Region (Italy) over six days of testing, in order to acquire repeated measurements of speed and lateral position at curves. The main objective of this study was to find relationships between speed choice, lateral position and route familiarity at curves. In particular, lateral position data in terms of trajectories were analyzed by considering the influence of road geometry and different test driving conditions. General findings about curve driving behavior are presented here, showing curve-cutting tendencies and higher radii of curvature of the trajectories selected than the radius of the curve itself. Furthermore, lateral position, in terms of lateral displacement from the lane centerline, seems to be affected by route familiarity: the radius of curvature of the selected trajectories increases with the repetition of travel on the same route. Moreover, some relationships between speed and lateral displacement at the considered curves were found.