Proudly home-grown – the CSIR’s accelerated pavement testing facility – the Heavy Vehicle Simulator (HVS) is a success story with global impact and one that has had a major impact on the design, construction and maintenance of roads locally and abroad for more than 40 years.
There is no doubt that the results obtained from the HVS programme over the past four decades will influence all road design undertaken currently in South Africa, and well into the future.
Roads are the lifeblood of an economy; at a cost of between R15 million and R8 million for a kilometre for a highway with a relatively short lifespan of 20 to 40 years, a country’s roads infrastructure has to be scientifically constructed and maintained to maximise costeffectiveness.
The HVS is a high-tech accelerated road-testing field lab with unique instruments that measure and analyse the engineering performance of road structures and material layers to test whether a specific road will have an acceptable lifespan. With the accelerated testing and laboratory associated research, researchers can simulate the damage over 20 years caused by heavy traffic volumes to road structures within a short time span of up to three months. These results are invaluable to taking corrective action in road design and selecting the best construction materials and methods when planning the construction of long stretches of new roads.
The latest model – the HVS Mk VI – is the result of continuous upgrades over the past two decades by the CSIR and its technology and commercialisation partner, Dynatest. Sporting numerous advantages over its predecessors, the new version costs less, is lighter and easier to tow on public roads and is less complex with increased wheel speed and test beam length.
Eleven of these massive roadside laboratories have been exported to active duty in the USA, Sweden, China, India and Costa Rica. The HVS has also been used for research in Finland, Slovenia and Poland. Over the past 18 years, the international programme has generated significant direct foreign income for the country – brought home as a result of quality research and technology development and sound commercial decision-making.
The largest and longest machine ever designed and built is under construction currently for the US Federal Aviation Administration.
The contribution of the two machines in use locally – one owned by the CSIR and the other by the Gauteng Provincial Department of Roads and Transport (GPDRT) – to our basic understanding of pavement material behaviour and advanced pavement engineering in South Africa has been immeasurable. GPDRT studies indicate that the quantifiable direct benefits of the HVS programme have been up to ten times more than the investment in the technology.
A benefit cost ratio of 10:1 was measured for the South African HVS programme in 2006. Every country that participates in the HVS programme has benefitted from improved, more cost-effective roads and a far better understanding of its road structure engineering and road materials behaviour.
More recently, the CSIR-developed HVS has been used locally to test the technology for using ultra-thin concrete technology for application in high-volume roads in South Africa. The original road design was imported from Denmark and adapted for local conditions. Working with the University of Pretoria, the Cement and Concrete Institute and local consultants, the CSIR used the HVS to test the final design and fast-track the implementation of the technology.
According to the CSIR’s Louw du Plessis, an international expert in accelerated pavement (road) testing, “The ultra-thin, high performance concrete is reinforced considerably for application in high-volume roads – seven times more steel is used than in ordinary continuously reinforced concrete.”
The South African National Roads Agency Limited has implemented the technology for high-volume roads on the N12 near the Gillooly’s interchange in Gauteng. In the Western Cape, the technology has been used on the N1 freeway between the Klip River Toll Plaza and the Huguenot Tunnel. The technology has also been used on an apron at the Oliver Tambo International Airport.
Over the next few years, CSIR research using the HVS will be aligned with the GPDRT’s strategy to cost-effectively and efficiently rehabilitate and upgrade Gauteng’s road network – one where more than 70% of the roads have reached the end of their design life-spans. Attention will be given specifically to public transport routes, freight corridors and the upgrading of unpaved roads.It is foreseen that the local and international HVS programmes will continue to thrive, with other countries and research groups likely to order HVS machines.