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T the invitation of the Malaysian Government the Tropical Sec- tion of the United Kingdom Road Research Laboratory is investigating ways of improving and cheapening tropical road building processes. team from the Laboratory comprising a civil engineer, a geologist, and two experimental officers is at present_in Malaya working in close co-operation with the Department of Public Works.
Work is proceeding simultaneously on a number of research projects. Some are primarily concerned with extending the scope of researches initiated in Great Britain and in other parts of the world to South East Asian conditions. Others such as the work on the stability of cuttings re- present the Laboratory's first re- searches on these topics.
The rapid increase in road traffic in South East Asia has unfortunately been followed by a similar increase in road accidents. In Malaya approx- imately 10 per cent of accidents on wet roads are directly caused by slip pery road conditions, and it is known that skidding is a contributing factor in many other accidents. Thus the provision of a non-skid road surface will considerably decrease the accid- ent risk on wet roads.
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One of the subjects being studied by the team in Malaya is the way the stone in the road surface is polished by the traffic passing over it. panels of selected road stones were prepared in England and set in a heavily trafficked road near Kuala
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ROAD RESEARCH IN MALAYSIA
Lumpur and a duplicate set was plac- ed in a nearby lightly trafficked hous- ing estate road.
The stones used included three Malayan limestones and three Ma- layan granites, together with two similar British stones whose perform. ance in English conditions is well known. The "skid-resistance" of each stone panel is being measured at re- gular intervals with a portable tester manufactured to a Road Research Laboratory design (Fig. 1).
Quicker Polishing
Results over the first few months confirm previous laboratory tests showing that the granites provide a more skid resistant surface than the limestones. Secondly, comparison with similar sites in England shows that the rate of polishing in Malaya is much higher, the stones becoming polished in less than a week on the heavily trafficked site. (see graph).
Further work on freshly laid pre- mix road surfaces is showing similar results, except that initially the bitu- men coating of the stone holds grit, giving a non-skid surface. When the bitumen is worn off however, which takes a few days on the heavily
trafficked roads but several weeks on the lightly trafficked ones, the stones quickly become polished.
Thus, because of the rapid rate of polishing, it becomes very import- ant to choose a stone which provides a more non-skid surface, particularly at sites such as junctions and bends
Fig.
1. Measuring the skid resistance of roadstones
by
J.N. Bulman
and
P.J. Beaven
Road Research Laboratory, UK
where vehicle accelerations are likely to induce skidding. Of the two com- mon Malayan roadstones it is found that the granite is always better than the limestone, which agrees with the behaviour of similar stones in Britain,
Deflection Beam
The
As in many other parts of the world, the high annual growth of traffic in Malaysia means that a con- siderable proportion of the network of older roads in the country will soon need to be strengthened. deflection beam, which was original- ly devised by A. C. Benkelman in the U.S.A., provides a convenient way of measuring the strength and uniformi- ty of existing roads, and could be of considerable assistance in planning a road strengthing programme.
The Road Research Laboratory is currently engaged in a long term test- ing programme in Britain, Central Africa and the Middle East aimed at the formulation of a set of deflection criteria for the assessment of the future load carrying capacity of exist- ing roads. The team in Malaysia is studying the effect of the local clim- ate, road construction methods, and subgrade soils on the deflection char- acteristics of selected lengths of road in the Federation.
The deflection beam is a simple de- vice that measures the transient de- flection of the surface of the road due to the passage of a standard wheel load. The beam has a pivoted arm which is sufficiently slender to pass between the twin tyres of a loaded lorry with dual rear wheels. As the lorry is driven slowly forward the tip of the beam, which rests on the road surface, detects the temporary depres- sion of the road due to the weight of the passing wheels. This depression is measured at the rear end of the beam by an ordinary dial gauge. Two light weight beams, specially develop-
Far East Architect & Builder September, 1966