This paper discusses the processes used to develop and adopt geometric design standards and criteria for highways and auxiliary facilities in the United States. Each State Department of Transportation (DOT) working through the American Association of State Highway and Transportation Officials (AASHTO) and the Federal Highway Administration (FHWA) have adopted minimum standards for the design of highway projects. The development of design criteria is a cooperative process between the various agencies and is based on research and practical experience to develop the criteria for each of the elements necessary for a complete design. Research topics are suggested by a variety of sources in response to a call by the AASHTO Standing Committee on Research (SCOR). The Transportation Research Board (TRB) of the National Academy of Sciences contracts for the performance of the research for the topics accepted by SCOR. Technical Committees review the product of the research and recommend disposition of the work. A summary list of recently completed research and updated criteria is included. While AASHTO is not a standard setting organization, it publishes the approved material for each of the geometric design elements in a series of documents. The published material is used as a standard or provides the basis for the standards developed by many transportation agencies. The documents published by AASHTO do not become a standard until they are adopted by an agency through a rulemaking process. The FHWA has an established process to adopt minimum standards for the National Highway System (NHS), including the Interstate System.
Samenvatting