NCHRP Report 563 contains the findings of research performed to develop design specifications for horizontally curved steel girder bridges. The developed specifications have been adopted by AASHTO and are included in the 2005 Interims to the third edition of the AASHTO LRFD Bridge Design Specifications.  Detailed examples showing the application of the specifications to the design of an I-girder bridge and a box-girder bridge are available from AASHTO. The material in this report will be of immediate interest to bridge designers. 

In the late 1980s and early 1990s, AASHTO and FHWA recognized the need to address problems with design and construction of horizontally curved steel girder highway bridges. AASHTO, through the NCHRP, embarked on an overhaul of the AASHTO Guide Specifications for Horizontally Curved Highway Bridges. NCHRP Project 12-38, "Improved Design Specifications for Horizontally Curved Steel Girder Highway Bridges," provided recommended load factor design (LFD) and construction specifications based on the state of the art that addressed many of the problems associated with the design and construction of these structures. 

While the LFD specifications were under development FHWA and others began conducting significant research that enhanced the understanding of steel bridge behavior in general and horizontally curved bridges in particular. The FHWA research included tests on a full-scale I-girder bridge, and knowledge of the moment and shear capacities of horizontally curved I-girder bridges resulted from this research. Analytical work, also funded by FHWA, resulted in the unification of the design equations for straight and curved steel girders.

NCHRP 12-52 was performed by Modjeski & Masters, Inc. with the assistance of Mike Grubb, Andrzej Nowak, Don White, and Chai Yoo.  The report fully documents the effort leading to the specifications and contains an extensive compilation of abstracts of horizontally curved girder bridge research reports.