Implementation of Next-generation Insulated Joints in Revenue Service

This article describes how the Transportation Technology Center, Incorporated, (TTCI) is installing and testing improved insulated joints (IJs) in five subdivisions. The article shows how TTCi is leading an industry-wide effort to improve the efficiency of bonded IJ in heavy-axle-load freight service. IJs are installed in mainline rail as dividers for track circuits that are currently used for train control. Working with Class I railroads, TTCi and IJ suppliers have designed several next-generation joints that have shown better performance than conventional IJs. After being tested in the laboratory and field, several of these joints have been installed in revenue service. A conventional IJ is a six-bolt, 36-inch-long joint installed with the joint center between crossties. Prior to 2004, the average service life of these joints was approximately 170 million gross tons (mgt). With improvements in materials, manufacturing and assembling processes, service life of IJs has more than doubled. The article states how most manufacturers are now guaranteeing 500 mgt of service life. However, this still falls short of the railroads’ goal of having the life of an IJ equal to the surrounding rail. With the implementation of improved installation methods and design improvements to the overall IJ system, the railroad industry is making significant steps to achieve this goal.