Page:America's Highways 1776–1976.djvu/330

 Publication has continued without interruption from March 1924 down to the present, although the frequency of issues has varied widely. Through the years, Public Roads again expanded to include articles on highway research and development from sources outside of the Bureau of Public Roads. Throughout its long history, Public Roads has maintained a high standard of scientific accuracy and literary clarity and, taken as a whole, is a remarkable chronology of the development of highway engineering and economics in the motor age.

The historic association between Federal highway researchers and their counterparts in the States is considered unique in Federal Government programs, past and present. Over the years, all of the States have conducted research in cooperation with Public Roads and contributed in countless ways to the program described here. One other important accomplishment in this longstanding Federal-State partnership has been the establishment of strong, viable research staffs, facilities, and programs in the States.

Another successful research relationship was established between Federal and State highway agencies and interested outside groups, including other Government agencies, the academic community and associations, national organizations, professional societies, and industry groups. These various bodies have aided in identifying needs and in planning research to fill those needs. They have assisted in the conduct of studies with time, manpower, funds, and consultation and have taken an integral part in the development and implementation of results.

One organization which has played a major role in coordinating modern highway research and disseminating the results is the Transportation Research Board (TRB), or, as it was known for half a century, the Highway Research Board (HRB). It was organized in 1920 as an agency of the National Research Council in the National Academy of Sciences. Its purpose was to “&thinsp;‘assist in outlining a comprehensive national program of highway research and coordinating activities thereunder; organize committees for specific problems; deal with ways and means; and act in a general advisory capacity.’&thinsp;” In recognition of the increasing emphasis on the “systems” or balanced approach to transportation problems, the TRB in recent years has modified its scope to include the development of other modes of transportation as they interact with highways. A more detailed discussion of the TRB and its relationship to the Federal Highway Administration research efforts can be found in Chapter 1 of Part II.

The Maryland State Roads Commission testing laboratory in 1929.

In the last two decades, considerable cooperative research has also been undertaken on an international scale. A notable example is the continued involvement of Public Roads in a number of research committees of the Organization for Economic Cooperation and Development (OECD). Their efforts have been particularly directed toward research for safer highway design and improved traffic operations. Since 1964 Public Roads has also worked with the International Road Federation in the collection and dissemination of information through a worldwide annual inventory of research and development activities.

In the early period of highway construction in this country, an understanding of the physical behavior of the major materials was developed primarily by trial and error, which led to the development of criteria and tests based, to a great extent, on empirical relationships. Much of the early research work consisted of testing large numbers of samples of highway materials to determine the essential characteristics of available materials and their suitability for roadbuilding purposes. Developments with different materials varied somewhat in time, but in general during the 1920’s and early 1930’s, the technology with respect to soils, asphalts and other bituminous materials, cement and concrete, and pavements, bridges, and other structures was developed.

Taking soil samples for field subgrade soil studies.

In the very early stages of the roadbuilding industry, little of a scientific nature was known about soils as road materials other than that clay soils were sticky and sadly lacking in vehicle support when wet; and that very sandy soils, while having fair performance when wet, were highly unsatisfactory when dry. Thus, the first effective modification of soils for unpaved roads consisted of adding sand to clayed soils and clay to excessively sandy soils in a more or less 324