The 4th Edition of the Standard Specifications for Structural Supports for Highway Signs, Luminaries and Traffic Signals was published in 2001 as a result of two extensive National Cooperative Highway Research Program (NCHRP) studies. This edition of the Specification incorporates an updated wind map, serviceability requirements, fatigue requirements for steel and aluminum supports, and guidelines for foundation designs. Many of these requirements are new to the Specification and had not been routinely considered in previous designs.

Since this rewrite, the NCHRP and several states have sponsored studies to supplement the original reports. NCHRP Report 469: Fatigue-Resistant Design of Cantilevered Signal, Sign, and Light Supports and NCHRP Report 494: Structural Supports for Highway Signs, Luminaries, and Traffic Signals are two such studies. Even though the findings are documented, it has become increasingly difficult for the Technical Committee for Structural Supports for Signs, Luminaries, and Traffic Signals (T-12) to review and develop specification language in a timely and appropriate manner. A deliverable of many recent NCHRP studies has been to develop specification language suitable for consideration by technical committees and adoption by the Subcommittee on Bridges and Structures. The reliability of the Specification can only be assured when the appropriate knowledge, based on current research, is incorporated into the Specification.

The project is complete. Recommendations for specification changes were adopted by the AASHTO Highway Subcommittee on Bridges and Structures during their annual meeting in July 2007.  (NCHRP Staff: D. B. Beal)