Techniques and approaches are discussed which could aid in analysis of the problem, generation of alternative solutions and selection of cost effective solutions for highway improvement projects. The speed differential vs. safety analysis of a highway facility is considered, and the development fna use of a speed profile for existing highways is described. Data are presented which indicate the need for careful analysis of a design with regard to deviations from the average speed of traffic on the highway factors affecting speed (upgrades, horizontal curvature, vehicle type, acceleration). Speed profile development and ways in which speed profile analysis may be used in design are outlined. The positive guidance technique is described which is based on the premise that the driver can be given sufficient information when he needs it, and in the form that he can best use it to avoid hazards. The extent and nature of such guidance is dependent on the hazard and its interaction with the drivers information processing characteristics. The application of the technique at a narrow bridge location is described, the application of the driver expectancy checks are discussed, and the procedure of evaluate safety improvements for roadside hazards on the Texas freeway system is outlined.
Abstract