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Show BUILDING OF MODERN ROADS The more ono looks over the lltL erature of modern road building, the better he real Ices how highly technical tech-nical a subject it is, and how great Is the need for expert advice in each" particular case. Is the road ono that will soon be worn out by heavy motor trucks? Also the wearing force of ordinary automobiles Is not to be disregarded. The fast driven car slipping speedily around turns, may grind out a road as fast ub tho heavy truck operated slowly. Second, what material will be most economical considering the distance to be transported, and how can it bo scientifically combined? On roads with light traffic, sand and clay combinations are being widely used. But tho sand and elay must if om-blned om-blned In the correct proportions. On gravel roads lt Is desirable to havo an admixture of 16 to 20 per ot ot clay or other binding material. In a macadam road there ls,the problem of finding a' crushed rock that will have tho flno grained quality qual-ity that promotes good wearv Yet our cities and counties will go on spending great sums, of money without with-out having thoroughly competent advice. ad-vice. It does not follow that a man needs a costly technical training.. Dut he needs'to know the basic principles (nnd to have had a lot of practical experience. ex-perience. t He should have seen a lot of different roads tried, and be able to assign the reasons for successes and failures. j A few years ago thero was n strong reaction against macadam I roads. Many road makers said they I were obsolete. On the old roads, the light patter of the horse's hoofs .merely created a soft dust that fitted fit-ted Into the Interstices and constituted constitut-ed a binder. But now the motor trucks and automobiles grind out the binder, as a millstone crushes the corn, and the wind blpws it away. |