THE NEW U.S.A. GRAVEL ROAD MANUAL

摘要

In the Unites States alone there are over 1.6 million miles (2.6 million kilometers) of unpaved roads. Most of these miles are classified as gravel roads, which imply that the top surface layer is made out of gravel of certain thickness. In several nations around the globe the road network is predominantly gravel surfaced. This network makes up the farm-to-market roads and therefore it is very vital to any nation's economy to properly maintain and design these roads. The maintenance of gravel roads varies widely from one nation to another, let alone within the same nation. Although the gravel road maintenance market has several manuals (1, 2, 3), none is comprehensive in nature and most are region specific. The Federal Highway Administration (FHWA) of the USA commissioned the South Dakota Local Transportation Assistance Program (LTAP) to develop a comprehensive manual that caters to the needs of the all agencies responsible for the maintenance of gravel roads. The manual was completed and distributed worldwide in 2001 and was well received. This paper briefly discusses the major highlights of the new manual. This new manual is developed to address all aspects of gravel roads maintenance, rehabilitation, and design. A technical panel from various regions of the United States was assembled to contribute to the contents of the manual and reflect their experiences thus giving the manual a national flavor. Several international road agencies were also contacted to include the practices of other nations and therefore add an international touch to the manual. The manual is written in a simple language so it can be understood by everyone involved in the road maintenance business from laymen operating simple equipments to the top managers who are faced with making crucial decisions. The manual contains over one hundred twenty five illustrations accompanied by captions to explain various maintenance practices. Several figures and tables are also part of the manual. The design section demonstrates the AASHTO method of determining the proper thickness of the gravel surface layer.