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Show H AS SOLVED PROBLEM OF "WASHBOARD" HIGHWAYS The mystery of the "washboard highways has been solved. At least very definite proof as to the real cause of the corrugations on gravell-' gravell-' ed highways has been envolved in a 1 series of experiments conducted the past four years by the engineering station of the Washington State College. Col-lege. "Cars with old-style high-pressure tires and no shock absorbers are causing by the the greatest part of the trouble, and it seems likely that when such cars are off the highways, the maintenance required will be only that needed to prevent ruts and to return re-turn thrown gravel to the roadbed," ' bulletin No. 19, published by the experiment ex-periment station contends. The bulletin develops the theory explaining ex-plaining the peculiar relations involved. in-volved. During the past summer, tests to check the published theory and laboratory tests were carried out at the State College with a car driven ' on a circular road where conditions could be closely controlled. Startling results were obtained, confirming the original conclusions-Driving conclusions-Driving 20 miles an hour in a model "T" Ford car equipped with high pressure tires and no stock absorbers, definite corrugations would appear in : less than 100 trips over the track. This was then repeated after smoothing smooth-ing up the road surface and adding four hydraulic shock absorbers, when I it was found impossible to form cor-- cor-- rugations although some 3600 trips 1 were run over the road. The tests ! were repeated using balloon tires and ; it was found that at the maximum i speed the circular track permitted, 20 miles an hour, no corrugations were formed, either with or without the shock absorbers. "So, if you must use the old Lizzie, fit it out with some balloons or snub-' snub-' bers, or both," asserts Dean H. V. Carpenter, director of the experiment ! i station and head of the college of I mechanic arts and engineering. "Then you and the car will be more comfor-( comfor-( table, Lizzie will last longer and so , will the roads. . |