Advances in Bonded Insulated Rail Joints to Improve Product Performance

Abstract

Insulated rail joints (IJs) are critical components of railroad track infrastructure. It is essential for IJs to maintain railroad track’s structural continuity while having an important role in track circuit design and implementation. The structural integrity and performance of IJs have been recognized as a key interest area by the railroads as a result of increasing average axle loads and train traffic. While there are many different designs offered by various manufacturers around the globe, the main approach utilized by heavy haul railroads in the US, Canada and many other countries has been to use adhesively bonded insulated joint bars between two rails. This approach offers the benefit of a composite assembly where the continuous bond between rails and bars offer a geometrically uninterrupted transfer of loads between rails and bars. The main components of a bonded IJ are joint bars, insulation material, adhesive, endpost, and bolts or other fasteners. This paper summarizes recent design improvements on these components. The main focus areas of the research are bar design, bar material selection, insulator and adhesive selection and using a novel endpost design for load transfer between two rails. Track support conditions’ impact on IJ performance has also been considered as a factor influencing IJ performance in track and incorporated in the study. The impact of insulation material selection on IJ performance is discussed. Finite element analysis was used extensively in the study where the analysis results were supported by laboratory and field testing. The results of the study indicate dynamic stresses in bonded IJs can be reduced nearly 40% in joint bars by a combination of design improvements on IJ components. Improved bar material properties are expected to lead to considerably reduced risk of bar fatigue failures in track.