Design and Construction of Two New Retrofit Combination Steel and Concrete Bridge Rail Designs

The Florida Department of Transportation (DOT) has several bridges that were constructed in the early 1970s and use two parapet bridge railing systems that are combinations of metal and concrete. These railings use an aluminum post-and-rail system anchored to the top of a concrete parapet. Both systems are used on high-speed roadways. The rails are often damaged by vehicular crashes and nuisance hits. The damaged aluminum rail components are expensive to fabricate and replace. Rail 1 is 2 ft 9 in. high and uses a cast-aluminum post with a round-tube rail anchored to the top of a vertical concrete parapet. Rail 2 is 3 ft 3 in. high and uses a cast-aluminum post with a rectangular-tube rail anchored to the top of a concrete Jersey-shaped parapet. Both metal rails are anchored to the parapets by cast-in-place anchor bolts. This paper presents the designs and details of two retrofit steel railings that use adhesive anchoring systems. These new railing designs are less expensive and easier to repair than the aluminum post-and-rail system. The retrofit designs presented in this paper meet the strength requirements of Test Level 4 of NCHRP Report 350. Design information and full-scale strength testing data used to develop the Texas DOT T401 bridge rail were also used to design these two retrofit designs. These retrofit designs were successfully installed on six bridges in Florida (approximately 4,000 ft).