Lateral Placement of Vehicles on Curves of Two-Lane Rural Roads as SafetyCri terion

摘要

This study focused on an in-depth examination of the driver behavior when driving through a curveon two-lane rural roads. Special attention was given to the lateral placement of the vehiclesdependent on the optical impression of the curve and the roadside features, as well as on the generaldriving behavior, such as speed and acceleration/deceleration. In order to obtain the lateralplacement of a vehicle passing through a curve a new method using video technique was developedat the Technical University of Dresden, Germany. This new approach allows the exactdetermination of the lateral placement of a vehicle on every possible cross section of the curve.Consequently the calculation of the frequency distribution on spots of interest and the driven pathof vehicles negotiating horizontal curves will be possible. Conflict areas, caused by criticalencroachments of the centerline or the edgelines could be easy and reliable detected directly on thecomputer screen and drawing by plots. This new developed method was applied on three curveswith different horizontal and vertical geometric alinements as well as different roadside features.The results reveal that the driven path can be very different from the built curve radius, according tothe variations in lateral placement as vehicles approach and traverse curves. A further result of thestudy is the fact that excessive speeds often caused critical driving maneuvers and consequentlylead to conflict areas especially with the opposing traffic. One of the main issues of this study wasalso the development of quantitative safety factors to evaluate the safety level of curves dependingon the driving behavior as well as on the geometrical and roadside features of the curves. Thesenew developed procedure was also applied in a case study.