. The Elimination of Skidding.
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ADRAWBACK that has always been existent in connection with the use of motor vehicles of all types is that of the danger of skidding. Although this characteristic is by no means desirable on the open road, it can, at times, assume alarming proportions in busy streets, where serious harm. can be inflicted upon persons and property by a heavy vehicle refusing to answer its steering or brakes on a
wet road. . One of the most interesting developments that have been made recently is that of producing a new system of road surfacing, which, to a large extent, eliminates this danger, and particularly is this progression to be welcomed in view of the fact that pneumatic tyres or resilient solids will, in all prob c18 ability, become more common in the futore than they are at present, it being recognized that tyres of these types are, in the main, more prone to skid in wet weather than are those of the normal solid-band variety. In order to understand the principle on which the new non-skid type of road is constructed, a consideration of whys and wherefores of skidding must first be grasped. If one took a section of a city street and analysed it carefully, it would be found that, above the road surface proper, there was in existence a layer of dirt, the thickness of the layer depending upon the efficacy or otherwise of the street-cleansing arrangements in force in the locality. A shower of rain converts this dirt into slime, and: the consistency thereof depends upon the degree of wetness. If only a alight shower is experienced, it does not become slippery, but when it is half wet is has the properties almost of lubricating oil. A good heavy downpour, of course, makes it very liquid. It is *hen it is in an oozy condition that it is most dangerous. It is then sufficiently thick to prevent itself from being squeezed out from between the tyre of the passing vehicle and the road surface, the result being that when any undue force is applied to the wheel it slips or skids. This would not occur if the tyres were in contact with the road.
Now., it is weil known that all non-skid tyre treads depend on a grease-piercing action for their effectiveness. If the tread can force its way through the grease.on to the road surface proper a skid is not so likely to result.. Modern road engineers; taking advantage of this fact, are therefore, making the actual
road surface into what is the equivalent of . a • nonSkid tread by means of impressing a well-defined pattern into it so that it consists of minute ridges and corresponding valleys, which allow the accumulated mud to squeeze out easily at the passage of a vehicle and thus allow the tyres to touch the road surface proper instead of pressing on a film of grease. Moreover, it will be seen that a road surface of this type need not he so highly cambered as is one that is waterproof and evenly faced, for it will drain more readily. Also, by giving the ridges and hollows a definite pattern, cleansing becomes a simpler matter, and by making these ridges and hollows of concrete, which is long-wearing, the life of the road surface need not be affected.
It may be-no far cry to the day when a skid on greasy town setts is a thing of the past, and a gratifying increase in safety will be the result.