Evaluation of a performance-based standards approach to heavy vehicle design to reduce pavement wear

Abstract

As a result of successful initiatives in Australia, New Zealand and Canada, the introduction of a performance-based standards (PBS) approach in the heavy vehicle sector in South Africa was identified by the Council for Scientific and Industrial Research (CSIR) as a research area warranting funding because of the potential benefits in terms of transport efficiency, road/vehicle safety and the protection of road infrastructure. Whereas most countries throughout the world regulate heavy vehicle use predominantly by prescriptive regulations, some countries have implemented a PBS approach, which involves setting standards to specify the performance required from the operation of a vehicle on a network rather than prescribing how the specified level of performance is to be achieved. As part of the “Smart Truck” or Performance-Based Standards (PBS) research programme for heavy vehicles in South Africa, demonstration projects have been designed and manufactured to comply with the safety standards of the Australian PBS system while the infrastructure performance standards are based on South African bridge and pavement design standards. In order to optimise road wear per ton of payload, the South African Mechanistic-Empirical Design Method, which is the basis of the South Africa Pavement Design Manual, was used to determine a Load Equivalency Factor for each baseline and each “PBS” vehicle combination. Eight typical South African pavement designs, both in the wet and dry conditions, were used in the analyses. This paper presents a summary of the assessment of 19 vehicle designs and the corresponding baseline vehicles in terms of their road wear effects. The paper shows that using such a performance-based standards approach, more road-friendly heavy vehicle design solutions can be found, resulting in vehicle combinations with improved performance in terms of road wear, efficiency, safety and environmental impact.