NCHRP Project 17-10 was undertaken in an effort to update the 1985 AASHTO `Standard Specifications for Structural Supports for Highway Signs, Luminaries, and Traffic Signals’ and its subsequent interim specifications. Because the 1985 `Supports Specifications’ is based on studies and reports that were published in the late 1960s, a significant amount of work was performed to incorporate new information that is currently available in design codes as well as in new industry practices. Major revisions include introducing the new wind map and current wind engineering practice, incorporating the new breakaway provisions of NCHRP Report 350, including a new section on fibre-reinforced composites, providing a comprehensive section on wood structures, and converting the entire specification to Systems Internationale (S1) units. The research consisted of an extensive review and analysis of theoretical and experimental research investigations, with major emphasis on adding new technical information in the proposed specifications and commentary. Several technical areas, identified as needing the most research, were investigated with the purpose of developing improved design criteria. These areas included new wind load criteria, allowable bending stresses for steel and aluminum, alternative design procedures, allowable dead load deflections, final deflected position, fibre-reinforced composites, wood structures, prestressed concrete design, span wire design philosophies, breakaway devices, fatigue design, loading across the diagonal, anchorage systems, foundation design philosophies, and corrosion protection systems. Other topics were also addressed as deemed necessary by the researchers. The proposed `Supports Specifications’ contains updates and state-of-the-art information on most of the topics listed above. New sections on fatigue resistant design, design of fibre-reinforced composites, and design of wood structures have also been added. A comprehensive literature study, including the review of research on design concepts and materials for highway sign, luminaire, and traffic signal structures, was conducted as part of this study. A survey of all major manufacturers of structural supports, as well as state departments of transportation (DOTs), was performed to solicit their input on technical items of particular importance that needed to be included in the study. The research team visited major support manufacturers to obtain information on manufacturing, testing, and quality control procedures. DOTs with special expertise in structural supports were also contacted. The updated `Supports Specifications’ and commentary resulting from this study are presented in a format similar to the AASHTO `LRFD Bridge Design Specifications’. This format will provide the engineer with a uniform design methodology and a document that is easier to use. Several enhancements in the proposed specifications ensure its user friendliness, such as a detailed table of contents, a side-by-side specification and commentary format, and a list of references for each section. This study also identified topics that need future research beyond what was accomplished in the project. A detailed discussion of these topics, as well as an approach for further investigating them, is presented in Chapter 4. The report also provides an implementation plan for moving the research into practice and discusses the work needed for future improvements to the proposed Supports Specifications. (A)
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