Dimensionerande körfältsbredder - Slutrapport

This report presents the results from a study of 90 km/h rural roads, where the effects of narrow vs. wide lanes on deterioration, safety, winter maintenance etc have been studied. Empirical studies have been performed of lateral positioning and speed on 16 road objects that vary with regards to lane width (3.25m respectively 3.75m) and presence of guardrail (with or without), other parameters have been kept unvarying. The effect of oncoming traffic on lateral positioning has also been studied. The effect on winter maintenance has been studied through surveys to contractors. Results show that narrow lanes, in comparison to wide lanes, reduce the life span of the road by 10-15%, and leads to a higher lifecycle cost on the whole. When faced with an oncoming vehicle the driver carries his vehicle farther away from the centerline, on average 2 to 30 cm depending on the situation and road design. No difference in accident risk has been observed between the two widths. An increased width results in higher demands on winter maintenance, but the effects are small compared to other influencing factors.