A methodology developed by Jordaan in 1985 to determine flow in any rank hour of the year for rural traffic is shown to be applicable to urban traffic. The methodology, which has become known as the 'beta method', was tested on 45 traffic flow data sets obtained from 12 counting stations in the metropolitan areas of Johannesburg and Port Elizabeth. Whereas studies of rural traffic have concentrated on hourly flows, it was found more appropriate to analyse urban traffic in terms of 15 minute flow rates per direction of travel. In studying the 15 minute peaking characteristics, it transpired that a three-region modelling approach was required.
A single degree of freedom model is proposed to simulate the response of a three-dimensional track structure subjected to a vertical oscillating axle load. It is shown that a dynamic model could be developed from the classical static Winkler-model. The dynamic model was successfully verified against a linear laboratory model. The course of progressive track settlement, resulting in the deterioration of the vertical track geometry owing to uneven settlement under repeated vertically oscillating axle loads is traced with the help of the model.
Guidelines for the geometric design of highways and streets are used to calculate minimum radii for horizontal curves and maximum curvature for vertical curves. Sight distance should always be greater than the stopping distance of vehicles. Current guidelines apply the stopping distance on a horizontal road to determine stopping sight distance, which results in an underestimation of the required radius or curve length on downgrades. A procedure was proposed that allows the engineer to take stopping distance on specific grades into account in road design.