Part 1 (1/2)

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PREFACE

AMERICAN RURAL HIGHWAYS ritten for use as a text or reference in courses dealing with rural highways and intended for agricultural engineers, students in agriculture and for short courses and extension courses The reader is assu, but the text is adapted pri the lines of the usual course in Highway or Civil Engineering

The text is intended to fahway iress, to indicate the various problehway adn and construction for rural highways in sufficient detail to establish a clear understanding of the distinguishi+ng characteristics and relative serviceability of each of the common types of roadway surface

Experience with classesand with trade school students in road ement of the material

Detailed discussion of tests of n has to a considerable extent been eli outside of the scope of the course for which the text is intended

In the preparation of Ahway subjects and to current periodical literature

Wherever direct extracts were ment appears in the text

T R AGG

AMES, IOWA, AUGUST 18, 1920

CHAPTER I

THE PURPOSE AND UTILITY OF HIGHWAYS

THE DEVELOPMENT OF HIGHWAY SYSTEMS

=Transportation Probles, are utilized constantly with little thought of how indispensable they are to the conduct of the business of a nation or of the intimate relation they bear to the everyday life of any coree to which a nation or a community perfects its transportation facilities is an index of its industrial progress and public highways constitute an important element in the national transportation systee citizen will think of the public highway only when it affects his own activities and that he will concern hihway iht forcibly to his attention through taxation or by publicity connected with the advancement of specific projects

=National in Scope=--The ihway system is of national importance just as is develophout a nation is a prerequisite to an adequate policy in regard to either It is inconceivable that any coreatly without so to many other parts of the country

Increased consumption, which always accompanies material prosperity, means increased production somewhere, and people purchase fros that they want Good transportation facilities contribute greatly to community prosperity and indirectly to national prosperity, and the benefits of highly ihways are therefore national in scope This fact has been recognized in Europe, notably in England, France and Belgiuely as national utilities

Until recent years, highway improvement in the United States has been subordinated to otherthe World War the inadequacy of the transportation system of the United States became apparent While such an unprecedented load upon transportation facilities may not recur for ress in highway improvement is necessary and in the United States the subject is now likely to receive attention commensurate with its importance

=Develophway improvement needed in any locality is dependent entirely on the demands of traffic In sparsely settled areas, particularly those that are semi-arid or arid, the amount of traffic on local roads is likely to be small and the unimproved trails or natural roads adequate But as an area develops either on account of agricultural progress or the establishhways both for business and for pleasure increases and the old trails are gradually iree, the new demands of traffic In sparsely settled areas, it is possible for the public to accohways to the physical condition thereof, and business isto the condition of the roads This is not always pleasant or econoement In populous districts, with diversified activities, it becomes imperative to have year-round usable roads in order to transact with reasonable dispatch the regular business of the industries Anything less will handicap norress

The advent of the reatly increased use of the public highways of agricultural areas, even of those that are sparsely populated, because of the convenience of the ht service Probably in excess of 90 per cent of the tonnage passing over the rural highways in the United States is carried by motor vehicles This class of traffic has really just developed and no one can predict what it will be in ten years, yet it has already introduced into the highway problem an element that has revolutionized methods of construction and maintenance

A different set of traffic conditions exists in those parts of the United States where large areas are devoted priricultural develophways connecting the industrial centers are indispensable adjuncts to the business facilities in such coe volu principally of motor vehicles The roads first selected for iricultural interests of the district, but rather those serving the industrial centers

Inter-city roads of great durability and relatively high cost are necessary for such traffic conditions

Not infrequently the transportation needs will require a systehways in the same community There are few areas in the United States where there is no agricultural develophway systeanization under which they are built andto the nature of develop inized that one or roups of traffic may be encountered and that the extent and nature of the improvement must be such as will meet the require first provided for, and that of lesser importance as rapidly as finances permit