Life Costing and Reliability Concepts in Concrete Pavement Design: the South African Approach

An empirical concrete pavement design method, based on mechanistic principles, was developed for use by the general practitioner. It was recognized that the outcome of the design process should not concern only layer characteristics and risk of failure, but also the area of pavement possibly afflicted by a particular mode of failure, the cost of maintenance and rehabilitation and eventually the life cycle costing of the pavement. This approach implies that the manifestations of different distress types need to be predicted together with cost implications. This paper discusses the background and development of the design package with special attention being given to the development of cost models as well as the validation of the method using data from trial sections and the road network. The design package can quickly pre-try the design, evaluate its quality and thus facilitate competent decision-making. The consequences of a certain pavement design are expressed in terms of decision variables such as % shattered concrete surface, or life cost, which are obtained from input random variables by means of Monte-Carlo simulation. The quality of pavement design is reflected by the values of decision variables and to facilitate evaluation and competent decision-making, certain criteria are given to guide the designer.