Research on Operating Speed Models of Free-flowing Passenger Car for Alignment Design of Highway

The objective of the paper is to develop a group of models of operating speed of free-flow passenger cars on freeway. The paper analyzed the driver's process of collecting and dealing with information in details. Based on a amount of field data, factors that influenced speed and corresponding rules of operating speed were definitely explored in this paper. A group of models used statistical methods were developed for prediction of operating speed of different alignments with design consistency concept. Compared with the result of field data, these models have the merit of high prediction accuracy of the 85th-percentile operating speed. The model could be applied widely in the alignment design approach of operating speed and traffic simulation. Finally, the paper had drawn a speed-profile of a freeway with these models. Thus designers and traffic engineers could diagnose and reduce inconsistency in design and ensure that most drivers would be able to operate safety at their speed along the entire alignments. This have settled good foundation for utilizing operating speed to rate design consistency. At the same time, it provids data support for geometric designer and researchers to use the operating speed concept and to establish the operating speed design criterion of highway in China.