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South Africa
South Africa
The South African Heavy Vehicle Simulator (HVS) program was established in 1968 and is the oldest and one of the most successful APT programs in the world. South Africa was the first to develop a mobile linear facility, the Heavy Vehicle Simulator (HVS), which can operate on in-service highways. Originally developed between 1968 and 1972, four HVSs have been in continuous use since 1982. More than 500 test sections have been trafficked.
The HVS has a hydraulically operated loading assembly carrying a single- or dual-tire test wheel, and capable of loading from 20 to 100 kN (4,400 to 22,000 lb) at speeds up to 14 km/h (8.6 mph). The wheel load has been increased to 200 kN (44,000 lb) for airfield pavement tests. Lateral wheel wander can be applied over a track width of 1.5 m (5 ft) with a normal distribution. One- or two-way loading can be applied over an 8 m (26.2 ft) test length. The HVS technology is now being applied at APT facilities in California, Florida, WES, CRREL in the U.S.A. and in Sweden-Finland.
The South African MLS was established in 1998 by MLS Test Systems Pty Ltd, in Stellenbosch. Thus far thirteen MMLS3 systems (1/3 scale load simulator) have been manufactured and exported to the USA , Europe and China. MLS test Systems has been involved in more than twenty APT research projects since its founding. The projects were located in southern Africa, Europe and the United States.
One full-scale loading system, MLS10, is a space frame approximately 10m long, 3m high and 2.4m wide. The MLS10 has four wheel bogies, each fitted with two 295/65 R22.5 (940mm diameter) or similar tires. The maximum load on each set of dual wheels is 6 tons (60 kN) at maximum speed. The system is designed to enable the bogies to travel at up to a maximum speed of 7.2 m/s (26 km/hr), when 7 200 axle loads are being applied per hour. The maximum load can be increased when the speed is reduced. Load control is semi-automatic with the load applied hydraulically. The operating dead load of the machine, including ballast weights is approximately 27 tons. Lateral movement of the device for simulating wander can be applied. Tire contact pressures is variable within the guidelines provided by the tire manufacturer's specification Each bogie has 12 sets of guide wheels. Each wheel set consists of two wheels, the inner one being a 250mm diameter flanged steel wheel to apply the load. The outer one is also a 250mm diameter steel wheel linking the bogie chain. In 2004, the World Bank sponsored an APT research project in Mozambique. The successful bidders opted to use the MLS10 as their full-scale APT equipment.
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