The influence of several vehicle parameters (i.e., vehicle weight, position of gravity center and type of wheel drive) was investigated for their impact on the curve design of rural highways; their impact has appeared to be significant for some combinations of horizontal curve radius, grade and speed when the vehicle motion in the driving mode has been examined. The investigation was based on a total of 52 different passenger car models; 3 representative two-axle truck models; and one tractor semi-trailer. The results, compared with the corresponding values for curve design accepted by the AASHTO-90 Design Policy (USA) and the RAS-L-95 guidelines (Germany) revealed that practically in most cases a cornering complying to the comfort or safety levels accepted by them is warranted, when the operating speed (85th percentile speed) coincides with the design speed and the positive grade is low. However, in other cases, considerable deficiencies were discovered especially in high design speed levels and/or high positive grades.
Abstract