Sight distance and speed choice

Lane keeping behaviour and speed choice while driving with restricted sight distances were studied on a winding rural road and a straight highway in a driving simulator. It became clear that the relationship between speed choice and lane keeping differs for these two kinds of roads. On the winding road lane keeping problems appeared likely to be a determinant of speed choice, and increased at restricted sight distances. A forced speed reduction diminished these lane keeping problems, and when subjects were free to select their speed they actually reduced their speed when the sight distance was restricted. On the straight road there was no indication of lane keeping problems with reduced sight distances. However, drivers did reduce their free speed. Explanations for the speed reductions are discussed.