NCHRP Report 469 contains the findings of a study on fatigue resistance of cantilevered signal, sign, and light supports. The report includes design examples illustrating the application of the fatigue provisions of the AASHTO Standard Specifications for Structural Supports for Highway Signs, Luminaires and Traffic Signals; guidance on design, installation, inspection, and maintenance of these structures; and recommended specifications for anchor rods. The material in this report will be of immediate interest to bridge and structural engineers, traffic engineers, and manufacturers.

Research performed under NCHRP Project 10-38 was published as NCHRP Report 412. Recommended specifications developed in that project, along with recommendations from NCHRP Project 17-10, have been incorporated into the AASHTO 2001 Standard Specifications for Structural Supports for Highway Signs, Luminaires and Traffic Signals.

The NCHRP Project 10-38 research also identified additional areas of study necessary to permit full implementation of the proposed revisions. NCHRP Project 10-38(2), "Fatigue-Resistant Design of Cantilevered Signal, Sign, and Light Supports," was initiated to address many of these areas. In particular, the research provides information on loads resulting from variable-message signs, methods for mitigating galloping effects, methods for tightening anchor bolts, methods for identifying structures and sign configurations susceptible to galloping, and characterization of importance factors. In addition, example designs were prepared to provide a comprehensive assessment of the effects of the design provisions developed in NCHRP Project 10-38. Finally, guidance on the design, installation, inspection, and maintenance of cantilevered supports was developed. The research was performed at the University of Minnesota, in Minneapolis, Minnesota.