Abnormal loads super routes – a strategic investment for promoting South Africa's economic growth

In many parts of the world, there has been an increased demand for moving larger and heavier machinery and industrial components during the past few decades. On the oceans, many of the 20 000 ton ships of yesteryear have been superseded by supertankers, which may exceed half a million tons. On land, large loads are required to be moved from factories or seaports to various inland destinations. Because of the absence of inland waterways and the limited capacity of the railways in southern Africa, these loads are transported on the road network. These large and heavy loads generally comprise equipment for electric power generation and chemical plants. Demands for such components are economically justified since the potential savings to these industries are vast assuming a useful life of about 25 years. When these large indivisible payloads, together with the combination of vehicles used to transport them, exceed 150 tons, 8 metres in width or 4,8 metres in height they are defined as Superloads and are of paramount interest to highway and traffic officials responsible for preserving the road network, infrastructure and furniture and minimising traffic congestion (Figure 1). The routes that they are allowed to travel are limited by bridge capacity and geometrics, involving mass, height, width and length restrictions. These critical routes are known as Super Routes. During the past few decades, numerous routes in South Africa have been checked, cleared and documented in order to ensure the safe movement of these loads. Since 1994, the number of major road authorities in South Africa has more than doubled. This includes the establishment of five new provinces and the South African National Roads Agency, the awarding of four 30-year concession contracts (to date) to manage and maintain sections of the national road network, and the re-definition of six metropolitan areas. The national Abnormal Loads Technical Committee recognised a need to identify and monitor a minimum number of strategic routes that need to be preserved for the movement of Superloads. This paper describes the development of an electronic Super Route Map, which can be used to graphically display relevant data related to these Super Routes. The system will be a useful tool for indicating to planning authorities the effect that a particular project such as a new bridge or a cable across a road could have on reducing or improving the capacity and effectiveness of a given Super Route. It will also be used by transportation consultants for preliminary planning of the movement of Superloads. The primary consideration is to arrest the increasing constraints being placed on existing routes by the encroachment of restrictive features that reduce the effectiveness of these strategic routes.