DRIVER SPEED BEHAVIOUR AND RURAL ROAD ALIGNMENT DESIGN

The results of comprehensive speed measurements on curves and tangents of Australian two-lane rural highways have been used to develop a set of curve speed prediction relations. Curve speed is dependent on the desired speed of travel pertaining to the road section and the curve radius. The desired speed of travel is largely affected by the overall alignment standard of the road section. A comparison of the observed speeds and conventional design standards indicate that, for design speeds less than 90 km/h, most Australian drivers traverse curves at speeds in excess of the design speed. It is recommended that the design criteria for low-standard alignments should be amended to bring them into accord with actual driver behaviour, and design procedures should be directed at ensuring that variations in alignment standard are consistent with driver expectancies. (Author/TRRL)