Development of Load Rating Procedure for Railroad Flatcar Bridges through Use of Field Instrumentation. I: Data Collection and Analysis

Because of budget constraints, many state and county highway agencies are often forced to develop innovative and economical replacement strategies for deteriorated bridges. One such option is to use a retired railroad flatcar (RRFC) for a bridge superstructure. Many states have found RRFCs to be successful and economical alternatives to more traditional structural systems. Although the performance of RRFCs has been satisfactory, there is little to no guidance in the AASHTO specifications for load rating these structures. Such inexperience has led some to take overly conservative approaches when rating these bridges. This paper, the first of two companion papers, presents the use of field instrumentation and controlled load testing on seven RRFC bridges located in Indiana. Stress data were used to gain an understanding of the in situ response of these structures, including global bending, secondary bending, and lateral load distribution. Proposed load rating guidelines presented in the second companion paper were developed using data from these load tests as well as other data found in the literature.