Road Tester Breakthrough
27 April 2006
MLS Test Systems of Stellenbosch, the specialist company best known for the development of pavement testing systems, last month received from Cape Town-based Petrel Engineering a road testing machine which is arguably the most modern around.
The contract was awarded to Petrel in September last year. M.D. Michael Franzen says the biggest challenge in building this machine, which weighs over 12 tons, is 3m high, 2.4m wide and 10m long, was that tolerances of the welded construction that had to be kept below 1mm (a real big 'switch watch').
If one considers that it is a dynamic machine - incorporating various mechanical, electrical and hydraulic components which was designed to deliver forces up to 6G, the engineering expertise required becomes truly remarkable.
"The unit basically will be put to work on roads, testing that the right ingredients were used in the right mix and correct format to ensure the durability of roads," Franzen says. "In other words it will enable one to establish within two days how well the road will stand up to the density of traffic and the loads of trucks, for example, before the road will start cracking up and forming pot-holes," he says.
In order to achieve this the road tester has four sets of wheels spinning at speeds of up to 30km/h inside its container.
Each of these wheels can exert pressure of up to 7 tons on the areas being tested. The drive mechanism is provided by linear induction motors. The configuration of technologies used in the tester has never been done in South Africa before, according to Franzen.
He says a big challenge to Petrel was to combine theoretical and practical ideas and to ensure that the many thousands of components were manufactured within tolerances under extreme pressure. All of the work involved with the tester was undertaken in the Western Cape.
The road tester is a South African patented product. The latest one will be put to work in Mozambique following finance from the World Bank. It will later be taken to Switzerland for further testing. If successful, further orders could follow from various countries around the world, one of which is China.
The cost of the machine comes in at around R9 million.
