Report Number

INLTAP-TR-2-2011

Sponsoring Organization

Indiana Local Technical Assistance Program

Performing Organization

Purdue University School of Civil Engineering

Date of this Version

7-2011

Keywords

bridge rehabilitation, retired railroad flatcar, bridge superstructure, load rating guidelines, railroad flatcar bridge, RRFC

Abstract

Due to budget constraints, many state and county highway agencies are often forced to develop innovative and economical rehabilitation strategies for deteriorated bridges. One such option is to use a retired railroad flatcar for a bridge superstructure. Railroad flatcars can be found in many lengths, making them versatile options for replacing bridges of a range of span lengths up to about 90 feet. Railroad flatcars are also completely modular and lightweight, allowing for quick construction. Within Indiana, as well as other states, several of these bridge structures have been in service for many years.

Although their performance has been satisfactory, there is little to no guidance in the AASHTO Specifications for load rating and inspecting these structures. This inexperience has led to many of these bridges being conservatively posted for traffic loads which are likely less than their actual capacity. Furthermore, inspectors may not be familiar with the details and areas which require special attention during field inspection. County and state highway officials also have little guidance when choosing which railroad flatcars are suitable for use as bridges.

This research is focused on the development of load rating guidelines for railroad flatcar bridges through the use of field instrumentation and controlled load testing. The proposed load rating guidelines intended to be a simple, yet not over-conservative, alternative to existing load rating procedures as well as those developed in previous research studies. Proposed inspection and acquisition guidelines were also developed based on field observations of numerous Indiana railroad flatcar bridges and discussions with county officials who possess a great deal of experience with these structures.

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