Show ROAD BUILDING Results of Tests Made Near of New Important changes in the matter of constructing state highways are likely to be made as a result of experiments being conducted by the Pennsylvania state highway These were begun two years when it became apparent that under the stress of increasing automobile traffic the standard macadam roads could not be kept in first class condition without expensive re- The various experiments have been made in the vicinity of in order to be frequently The first was a piece of road built on what is called the penetration system in Upon the usual foundation was placed a layer of crushed half the thickness of that ordinarily used in macadam and in to the interstices was poured an oil containing about 80 per cent of The surface of the road was covered with dry stone screenings and the mass Although subjected to heavy traffic for over a the road shows but little evidence of wear and is nearly Two pieces of road closely resembling the ordinary sheet asphalt which were built last show practically no evidence of Telford laid by were used as a and on top of this was placed a mixture of crushed stone and mixed hot and A surface of fine stone screenings and asphalt was placed over Another experimental road now being constructed has a Telford upon which is placed a layer of crushed stone and asphalt mixed with stone cold and the asphalt The surface is sprinkled with hot oil and covered with a thin coating of coarse stone These various methods exceed the cost of ordinary macadam by at least per but this extra cost is supposed to be more than by the reduced cost of The department is also experimenting with a dust layer for ordinary macadam roads known as It is a by-product of wood pulp The liquid has the consistency and appearance of It is soluble in and one of its peculiarities is that each succeeding rainfall renews the bonding or cementing qualities of the A piece of road dressed with it early this season is being carefully watched by the Town and |