In Which We Start Testing Roads…

October 15, 1958

The inaugural ceremony for the AASHO Road Test took place in the city of Ottawa, Illinois, which is located about 80 miles (128.8 kilometers) southwest of Chicago. The purpose of this road test, which was sponsored by the American Association of State Highway Officials (AASHO) and supervised by the Highway Research Board (now the Transportation Research Board) of the National Academy of Sciences, entailed conducting scientific studies of the performance of highway pavements when subjected to repeated passages of vehicles of various weights and sizes.

This effort was far from being the first one undertaken to assess the most optimal materials and designs for the development of long-lasting roads. An early and well-documented example of this type of test involved the Bates Experimental Road in Illinois during the early 1920s. The Illinois Division of Highways built a 2.5-mile (four-kilometer) test segment on state property near Springfield to determine the best materials to use for rural roads carrying major truck traffic. This road test concluded that concrete was the best material for highway building and provided a precise design to maximize the life of concrete roads.

The U.S. Bureau of Public Roads (BPR) conducted several loading tests on concrete pavement during the 1930s. Systematic efforts to gauge the service life of highway pavements and the impact of wheel loads gained new momentum after World War II. AASHO provided strong leadership and support when it came to those efforts. In 1948, for example, the association established formal procedures for launching and managing road tests.

In general, these research projects were financed jointly by two or more states to provide data for the development of longer-lasting pavements to handle ever-increasing traffic nationwide. These first of these projects was carried out in Maryland in 1950 and 1951. This effort, known as Road Test One-MD, was administered by the Highway Research Board and financed by the District of Columbia and 11 states – Maryland, Connecticut, Delaware, Illinois, Kentucky, Michigan, New Jersey, Ohio, Pennsylvania, Virginia, and Wisconsin. The Maryland study used an existing road near the town of La Plata to test the impact of round-the-clock truck traffic on concrete pavements.

Following this project, the Western Association of State Highway Officials (WASHO) sponsored a road test in 1953 and 1954 in Idaho at the suggestion of the AASHO Transportation Committee. The WASHO Road Test focused on the impact of heavy truck traffic on flexible (asphalt) pavements. This road test – likewise administered by the Highway Research Board – was financed by the Idaho, California, Colorado, Nevada, New Mexico, Oregon, Texas, Montana, Utah, Washington, and Wyoming highway departments.

Plans for a third road test, which would be conducted under the aegis of the Mississippi Valley Association of Highway Officials (representing Midwestern states), were abandoned in favor of a more comprehensive research project sponsored by AASHO.

The noontime ceremony officially launching that comprehensive project on October 15, 1958, included a ribbon cutting by Governor William G. Stratton of Illinois. Among those speaking at the ceremony was Ellis L. Armstrong, who had recently been appointed BPR commissioner.  “Today we are opening the most important section of highway in the country,” he proclaimed to those in attendance. “For highways are built for only one reason–to serve the people. And this road is not different in that respect . . . . The benefits from this test road . . . will begin to serve the Nation at the earliest possible date.”

Claude R. McMillan, AASHO president and South Carolina chief highway commissioner, likewise spoke at the ceremony. He asserted, “This is a big day for highway transportation in the United States and everywhere.”

Over the next couple of years, the AASHO Road Test was carried out along a seven-mile (11.3-kilometer) track of two-lane highway between Ottawa and the city of LaSalle. (The track was part of the future alignment of Interstate 80 in that area.) The road test focused on the impacts of moving truck loads on a variety of both asphalt and concrete pavement designs. There were a total of 836 segments with six test loops and 16 bridges along the track, all built with different materials and engineering concepts.

The U.S. Department of Defense provided cars and heavy-duty trucks that were driven over this experimental stretch of highway relentlessly to see which pavement segments lasted the longest in the best possible condition. Information on these segments was crucial in advancing knowledge about structural design, pavement performance, and the impact of heavy loads.

Overall, the AASHO Road Test encompassed the largest and most substantive pavement research performed in the 20th century. Its results have proven to be highly influential with respect to highway design and construction. For more information on the AASHO Road Test and its legacy, please check out https://www.fhwa.dot.gov/infrastructure/50aasho.cfm and http://onlinepubs.trb.org/onlinepubs/circulars/ec118.pdf.

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