proved to be impractical. Another experimental trackway road, this one of bricks, was built on the Department of Agriculture grounds in Washington in 1900. The most important of these early experiments, however, was the oil treatment of a 4,650-foot section of the Queens Chapel Road in the District of Columbia.
In 1900 the automobile was not a significant cause of road dusting, and road oiling was practically unknown outside of Los Angeles County, California, where 6 miles of road were oiled in 1898 to lay the dust “which, churned beneath the wheels of yearly increasing travel during the long dry season in that region, had become a most serious nuisance.”[1] The Queens Chapel Road had a surface of sandy clay and loam. This was shaped up and sprinkled with oil delivered by an ordinary water-sprinkling wagon.
The ordinary sprinkling wagon was found quite satisfactory, especially as the weather was warm, so that the oil ran quite fast enough to be gradually taken up by the surface and not so fast that it would flow into the side ditches, as would have been the case had the required amount been applied at once.[2]
The oil used for this experiment was “that which is left of crude petroleum after such volatile substances as naptha, kerosene, benzine and gasoline have been extracted.” The results of the treatment appeared to be good, but the OPRI elected to reserve judgment on its ultimate effectiveness:
This road was treated several weeks ago, and so far as we are now able to judge the new system is a success as a dust layer. We believe that where roads have so much traffic and dust as to require the use of the sprinkling cart in dry weather, the residue oil, or roadbed oil, as it is called by dealers, could be used very effectively and economically. The fact that it settles the dust and kills weeds was first recognized and utilized by the West Jersey and Seashore Railroad. It is now being applied annually to about thirty of the leading railroads throughout the country, and its use is being gradually extended to the ordinary country roads. It is claimed by some that the application of crude oil will make a surface impervious to water, and consequently comparatively free from frost and mud. If this be the case, oil will supersede gravel and stone in the improvement of country roads. The test of time alone can settle this very much disputed question.[3]
Out of these early experiments there gradually evolved a new program, the object of which was not so much to demonstrate good construction practice as to acquire new knowledge and experience.
In 1908 the OPR began a study to determine whether blast furnace slag could be made into a suitable road aggregate by mixing it with lime, limestone, tar or asphaltic road oil. This investigation had an immense economic potential, since about 20 million tons of slag were produced annually in the United States, most of which had no commercial value.
Between 1908 and 1916, the OPR supervised or participated in the construction of several dozen experimental roads, ranging from earth-oil mixtures to Portland cement concrete and paving brick. These were inspected periodically and their service evaluated and correlated with the laboratory records of the materials that went into them. Eventually the OPR engineers drew up specifications for each type of construction based on their experiences with these experimental roads and the numerous object lesson roads. These specifications were published in bulletins, some of which went into five editions, and were widely used by counties, States and engineering colleges as references. In particular, the OPR’s specifications for bituminous road binders became the standards for the industry and were adopted by most of the State highway commissions.
Electric car on steel track at the Trans-Mississippi Exposition at Omaha in 1898.
The Dust Nuisance and Road Preservation
The light duty macadam and gravel roads constructed during the Good Roads Movement served their purpose very well until appreciable numbers of automobiles began to use them.[N 1] Many engineers, Page among them, were convinced that the solution to this troublesome problem lay in using something other than stone dust or clay as a binder for stone and gravel roads. Hot-laid asphalt paving had been used on city streets in Europe and the United States since the early 1870’s, but was considered far too expensive for country roads. However, liquid materials containing bitumen cement, such as petroleum, coke-oven tar and water-gas tar, were plentiful and cheap and seemed promising as dust layers.
An opportunity to test these materials came in 1905 when the Madison County Roads Association and the city engineer of Jackson, Tennessee, sought the OPR’s cooperation in experiments to determine the value of coal tar and petroleum oils for building dustless roads. Page agreed to participate by supplying expert supervision and the facilities of the OPR laboratory. The Tennessee experiments were moderately successful, and 3 years later, in 1908, the tar and residual petroleum oil (asphalt) treatments were pronounced “on the whole very satisfactory,” but the crude oil treatment had disappeared, leaving the roads as dusty as ever.[5]
67
- ↑ A. Rose, supra, note 7, p. 101.
- ↑ Bureau of Public Roads Annual Report, 1900, p. 287.
- ↑ Id.
- ↑ 1971 Automobile Facts and Figures (Automobile Manufacturer’s Association, Detroit, 1971) p. 18.
- ↑ Office of Public Roads, Progress Reports of Experiments With Dust Preventives, Circular No. 89 (U.S. Dept. of Agriculture, Washington, D.C., 1908) p. 26.
