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Show Ruined Pavements Caused by Speed, Not Weight of Loads That it is tin) speed of heavy loails, rather than the weight of the load itself, it-self, that ruins pavements is the conclusion con-clusion readied bv Kovernmcnt authorities authori-ties who are invest itfatuiK various phases of the automobile transportation problem. , , Experiments begun by ffovcrnment experts to determine the destructive effect ef-fect of impact on pavements and to find a remedy show some striking results re-sults Conclusions now announced reveal re-veal that a weight of 77.W pounds on the wheel of a truck, moving at a speed of fifteen miles per hour, becomes OuO pounds in its desirucrivc ettoc it the wheel has a drop of one. inch. Mien a drop is vcrv readily caused by any small obstruction or crack in the pavement. pave-ment. , ' ... A cushion pavement ot asphalt con struction is expected by engineers to solve the impact problem. Tbe cushion will absorb the shock so as to reduce the shattering effect of impact on the foundation. Kxpemlilure lor construction construc-tion and maintenance of highways outside out-side of cities is now averaging some $.300,000,(1(10 a vcar. J. N. Mackali, chief engineer of the Marvlnnd state, roads commission, is I now' facing the' problem of restoring ! pavements' shattered by the impact of I heavy truck traffic, on concrete roads j lead in" out of Baltimore and construct-ed construct-ed as recently as and 1914. Mack- i all savs of these roads: ' "Both of these cenient-couerete roads I have reached the cud of their lives. They show many cracks and re disin-1 disin-1 tegr'ating. We' liavo tried patching them without success and are now covering cov-ering them with one-and-onc-halr-inch binder course and onc-and-oue-half-inch topping course of asphalt. |