Evaluation of the FDOT Variant of the Modified Kansas Corral Bridge Railing (9-8132-2)

The objectives of this portion of the project were to: 1. Determine ifthe subject variant of the Modified Kansas Corral (MKC) railing complies with the requirements of the AASHTO LRFD Bridge Design Specifications and NCHRP Report 350, Test Level 4. 2. Prepare a comprehensive report of the research findings that is suitable for submittal to the FHW A by the FDOT as part of a request for acceptance package. 3. If required, perform a full-scale crash test to verify the crash performance of the MKC railing. The AASHTO LRFD Bridge Design Specifications give guidance on geometry of the traffic face of railing that can be expected to provide acceptable performance in full-scale crash tests. The relationships between geometric factors and performance are approximate and are based on information available at the time the Specifications were prepared. Since that time, many tests of bridge railings have been performed. Information from those recent tests was compiled and compared with the geometry of the MKC and with provisions of the AASHTO LRFD Bridge Design Specifications to provide insight concerning acceptability of the geometry of the MKC railing. The FDOT variant of the MKC is similar to the original Kansas Corral bridge rail. Offset between the post and beams is 38 mm (1 1/2 inches) on the FDOT variant and 50 mm (2 inches) on the original Kansas Corral, and the post height is 305 mm (12 inches) on the FDOT variant and 330 mm (13 inches) on the Kansas Corral system. However, portions ofthe openings on the FDOT variant of the MKC have been reduced by the placement of a 152 mm (6 inch) curb in the openings and flush with the upper beam face, this modification should enhance impact performance by reducing the snagging potential. The overall height of both systems is 813 mm (32 inches). Based on the comparison to the previously tested bridge rails and AASHTO guidelines, the FDOT variant of the MKC bridge rail is believed to meet the crash test performance of NCHRP Report 350.