Abstract
Driver's functional visual environment are decided mainly by roadway alignments and cross sections. In this paper, studies about sight distance are reviewed, and relatively new concept, “preview sight distance (PVSD)”, which definition is re-examined by author, is proposed as a evaluator of driver's functional visual environment. Though horizontal and vertical alignments are usually defined separately on two-dimensional plane, the three-dimensional exact definition of road geometry including road alignments and cross sections is introduced. At last, utilizing this three-dimensional road geometry definition, the algorithm for calculating PVSD, at any point of driver's view simultaneously, is proposed.
