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economy and of safety. One of the peculiar difficulties encountered by the local communities with regard to bridges and culverts is that the great majority of these structures are comparatively small, so that those in responsible charge do not feel warranted in incurring the expense incident to the employment of skilled engineering assistance. Requests are continually being received for information concerning the use of concrete and other materials for bridges and culverts. Such information is being collected and disseminated. One bulletin dealing with this subject has already been published and others are in course of preparation. The published information is supplemented by personal inspection, advice, plans, and superintendence by the engineers of the office when request is made through the proper local authorities.
TESTING OF ROAD MATERIALS.
In the routine testing and examination of road materials great progress has been made along established lines. The total number of samples tested during the year was 685, which were received from a widely distributed area, including 42 States and Territories, Porto Rico, Canada, and Germany. During the year 324 samples, mostly bitumens, were received for examination in the chemical laboratories. This is nearly twice the number examined during the previous year, and more than four times the number examined in 1909. Much valuable work has also been done in standardizing methods of testing and examining road binders and other materials. It has been found that the addition of a small proportion of cement to blastfurnace slag screenings increases the cementing properties very greatly. These investigations will be continued both in laboratory studies and in service experiments in the field during the coming year. Research work in concrete has been carried on with increased vigor. These investigations include a study of oil-mixed cement concrete, principally with reference to its road-building and water-proofing properties, and also a study of the expansion and contraction of concrete while hardening, a subject of much importance in connection with concrete pavements.
INVESTIGATION OF ROAD BINDERS AND DUST PREVENTIVES.
Investigation of the problems of dust prevention and road preservation has occupied much attention during the year. Commendable progress has been made in the several lines of work. Demand for specifications covering the various types of bituminous binders and bituminous road construction is continually increasing. During the year 81 sets of specifications were furnished, on request, to officials in 20 different States, and also to the Reclamation Service, the Navy Department, and the War Department.
Many worthless road preparations have been and are still being manufactured and sold to the public through ignorance on the part of both the producer and consumer with regard to the characteristics of such materials requisite to meet local conditions. These materials are sold under trade names, and as a rule carry no valid guaranty of quality. Correct specifications for such materials are. therefore, much needed for the protection of the public.
The influence of the work already done by the office along these lines is shown in the production of better and more uniform materials on the part of the manufacturers.
While great progress has been made in the improvement of methods of bituminous road treatment and construction during recent years, the subject is still in a stage of development. For this reason the work carried on by the office is of the greatest value to the country in general. Tests and methods of analysis are being standardized, and the behavior of the various materials in actual use is being more definitely determined, while the development of economic and practical methods of construction suitable for various local conditions is being perfected. Much research work along these lines has also been carried on, and will be continued during the coming year. These cover such subjects as the effect of various methods of distillation on the physical and chemical properties of tars, investigations on the economic utilization of various coke-oven tars in the preparation of road binders, studies on the effect of light and the effect of weathering on various bituminous materials, and other allied subjects.
STATISTICAL AND ECONOMIC INVESTIGATIONS. An investigation completed during the year shows that the total road mileage of the United States, exclusive of Alaska and insular possessions, is 2,210,857 miles, of which only 187,910 miles, or 8.49 per cent of all our roads, are improved. But in 1904 only 153,531 miles, or 7.13 per cent of our public roads, were improved. Thus in the five-year period 1904–1909 the increase in the mileage of our improved roads has been 34,379 miles. Investigations to ascertain the economic effect of road improvements on rural communities were begun in 1910 and carried on during the past year. These investigations give promise of exceedingly valuable data and will be continued during the coming year. Investigations dealing with road administration and road management have been inaugurated during the year. It is believed that when these investigations are completed and published they will result in the complete reorganization of the present system of road administration in many communities throughout the country. Information is also being collected in regard to taxation, bond issues, and the use of convict labor in road building. This work will be continued during the present year.
EXHIBITS AND ROAD-IMPROVEMENT TRAINS.
Another important feature of the educational work of the office during the year was the road exhibits displayed at Knoxville, Tenn., during the Appalachian Exposition, and also at Chicago, Ill., during the National Land and Irrigation Exposition. These exhibits attracted so much attention at these expositions that various railroad companies applied to the office for the privilege of installing them on cars where they could be shown at the principal towns along their lines. An arrangement was accordingly made with the Pennsylvania Railroad, the State Highway Department of Pennsylvania, and the Pennsylvania State College to cooperate with the office in operating a road-improvement train throughout the State of Pennsylvania. The train carried an exhibit car, which contained not only the models referred to above, but also a large number of enlarged photographs and pictures illustrating various features of the road subject, together with a lecture car, in which illustrated lectures were given at each stopping place. Two other cars were provided with exhibits of modern road-building machinery. Another similar train was started May 1, 1911, over the lines of the Southern Railway. The success of this project is shown by the fact that during the year approximately 65,000 people attended the lectures and viewed the exhibits. This work will be continued along similar lines during the coming year.
OIL-MIXED CEMENT CONCRETE.
A very important discovery, that of oil-mixed cement concrete, was made during the fiscal year 1910. Laboratory and service investigations show that the Portland cement concrete of everyday use may be rendered waterproof at very slight extra cost simply by the addition of residual mineral oil. The possibilities for an increased and more efficient usefulness of concrete by the application of this method of damp-proofing are manifestly numerous.
A public patent, which has aroused much interest throughout the country, has been granted to Mr. L. W. Page, Director of the Office of Public Roads, for mixing oil with Portland cement concrete and hydraulic cements giving an alkaline reaction, so that anyone may use this process without the payment of royalties.
The crop year 1911 has been one of extremes. Light rainfall and high temperatures reduced the magnitude of many of our crops, and this reduction increased the price. The cotton crop was above the average and its price declined heavily.
The study of agriculture is progressing along scientific and practical lines and the work done indicates better mental equipment.
While the total values of crops in 1911 are not so high as in 1910, there is great abundance for all purposes. I am gratified to see the beet-sugar tonnage reach nearly the 600,000 figure. It indicates that we can make our sugar. We still buy nearly $100,000,000 worth of sweetening.
The details of the operations of the department will be found in the reports of the heads of the several bureaus, divisions, and offices. Respectfully submitted.
Secretary of Agriculture. WASHINGTON, D. C., November 25, 1911.