This research developed recommended guide specifications for horizontally curved highway bridges based on current practice and technology. The proposed specifications that resulted from this work were adopted by AASHTO in 1999.
The first AASHTO Guide Specifications for Horizontally Curved Highway Bridges, issued in 1980, was based on research performed in the early 1970s. The 1980 Guide Specifications included design provisions for curved steel I-girder and composite box-girder bridges. Design and construction experience since then has demonstrated some major deficiencies of the Guide Specifications that can result in overly conservative designs. Fabrication and erection provisions were also missing, and there was insufficient guidance on analytical procedures for both preliminary and final design.
The findings of this study are documented in NCHRP Report 424, "Improved Design Specifications for Horizontally Curved Steel Girder Highway Bridges." The report provides a full description of the research that was performed to develop the improved specifications. The report is particularly noteworthy because it identifies major departures from the current specifications and because it explains the reasoning behind these departures. The report should prove to be a valuable resource document for design engineers who are interested in understanding the theoretical and historical basis of the specification provisions.
The unpublished appendices listed in NCHRP Report 424 can be found here:
