Road networks and other transportation systems commonly looked upon as separate entities should be considered as inter-dependent sub-systems to be managed as an interrelated whole. Just as a Metropolitan entity requires co-ordinated planning and control, so does its transportation system. The emphasis must be on positive measures aimed at optimum use of the whole road system and various transport modes, rather than restrictive legislation against the indiscriminate and unrestrained use of cars. A farsighted and enlightened investment policy for urban transportation is required together with an equitable method of vehicle taxation combined with pricing of roads and parking. If necessary, metropolitan transportation boards should be established for this purpose. Also required are comprehensive urban and regional transportation planning techniques to allow for future interaction between land use and transportation needs on a highly flexible basis. Improved design criteria and new types of transport modes are suggested as possible means of easing peak hour congestion. Freeways should be designed to enhance rather than destroy the urban scene. Vehicle-free pedestrian precincts appropriately located in relation to freeways and strategically located garages, offer hopeful prospects for improving the quality of central city living. No less important than freeways is the establishment of an efficient system of public transport, but public transport alone will not provide the whole answer. The only sensible and practical approach is the synoptic one in which all forms of transport are taken into account together with all aspects of metropolitan planning.
The extent to which chloride contained in concrete can be bound by two South African cements has been measured. Estimates of the residual concentration of chloride in the pore solution in concrete are presented. The residual chloride concentrations are compared with published threshold concentrations for the corrosion of reinforcing steel. A maximum tolerable limit for the concentration of chloride in the mixing water of concrete is proposed. Methods of minimizing the risk of corrosion are considered.
The paper gave a systematic descriptionption of each layer of soil from the surface down to bedrock which provides the basis for tbe first assessment of the engineering properties of the soil. The important descriptionptors for a layer of soil are moisture condition, colour, consistency, structure, soil type and origin (MCCSSO). Standard terms for covering the range of each descriptionptor were given, together with standard graphical symbols for each soil type. Consistency assessments were extended to include tbe range of rock materials. The significant characteristics of the Southern African soil profile were discussed.