Cost and performance comparison of U.S. overhead sign support structures

Document Type

Conference Proceeding

Publication Date



Recent developments in fatigue analysis and design of overhead sign support structures prompted AASHTO to update the Standard Specifications for Structural Supports for Highway Signs, Luminaires, and Traffic Signals in 2001. An earlier version of the specification was published in 1994 and, according to recent studies, did not adequately address the issue of fatigue. Updating existing sign support structures to comply with the AASHTO 2001 sign specification may result in a substantial expense to the state departments of transportation nationwide. A method was developed to analyze and evaluate overhead sign support structures for comparison based on cost and performance. The method was then applied to sign support structures across the United States to determine the best performing and most economical designs currently in use. To determine the estimated fatigue life of critical connection details, the evaluation of overhead sign support structure performance was based on dynamic analyses of finite element analysis models. Cost evaluation was based on structure weight and its relative constructability. Performance and cost metrics were combined to establish an optimization parameter, providing a quantitative measure of comparison between overhead sign support structure designs. It is therefore a representation of both effectiveness and economy and, because the performance measure is based on fatigue, it is consistent with current trends in overhead sign support structure design. The method may be used by all state departments of transportation and for all different types of sign support structures.

Publication Title

Transportation Research Record