The standard requirements for and the aims of vegetation/verge clearing and mowing are poorly founded. There is not sufficient knowledge about for instance effects such as trafficability and traffic safety. The aim of the project was limited to studying the impact of vegetation/verge clearing and mowing on sight distances and whether road users change their behaviour with respect to speed and lateral position. In 1995, five test sections were chosen. These were cleared according to a regular plan. A control section where clearing was not performed was also chosen. Sight distances were measured before and after clearing the five test sections. Before clearing, between 74% and 96% of the distances were measured with at least a single stopping sight distance (110 m). After clearing, an increase in sight distances of approximately eight percentage units was measured. The corresponding values for double stopping sight distances (220 m) were between 22% and 63%, with an improvement of approximately 16 percentage units. Journey speed was measured on both test sections and the control section before and after clearing. Spot speed and lateral position were measured on the test roads both on straight sections and on left-hand curves. The result of the study was as follows: (1) no significant increase in journey speeds was observed; (2) spot speeds increased on straight sections and on curves after clearing; (3) in the middle of and when leaving left-hand curves, cars were closer to the middle of the road after clearing; and (4) at the entrance to left-hand curves and on straight sections, the lateral position of cars was not changed after clearing. (A)
Abstract