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    Evaluation of Ballast Particle Movement Using SmartRocks for Track Transitions

    Published: 2018

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    Ballast is a critical layer in the railroad track substructure that provides track drainage and supports track upper structures and railway trains. Many types of track problems, such as differential settlement, ballast migration, and track geometry degradation, are associated with ballast. Both laboratory and numerical research efforts have been undertaken to study ballast performance. These show that individual ballast particle movement can strongly affect the overall track performance. To measure the movement of an individual ballast particle, a wireless ballast-shaped device (called a “SmartRock”) equipped with a nine-degree-of-freedom inertial measurement unit was used. This device can be placed in the ballast layer to record and send back the real-time ballast particle motion through Bluetooth, such as accelerations and angular velocities. A ballast performance test/evaluation was conducted at the Transportation Technology Center in Pueblo, CO, which is a world-class railway research and testing center. The test sections include a bridge approach and an open track, both located in the same five-degree curve. The bridge approach had differential track settlement and required frequent maintenance based on a historic track maintenance log. The SmartRocks were instrumented west of the bridge approach and in the nearby open track. The second stage of this test investigates the effectiveness of under tie pads on reducing the vibration at the tie–ballast interaction. Therefore, the bridge approach was installed with a 50-tie track panel with under tie pads. The ballast performance was evaluated based on the analysis of the measured acceleration data. Detailed results and conclusions are presented in the paper.


    track transition, ballast particle movement, SmartRock, under tie pad

    Author Information:

    Gao, Yin
    Transportation Technology Center, Inc., Pueblo, CO

    Liu, Shushu
    The Pennsylvania State University, State College, PA

    McHenry, Mike
    Transportation Technology Center, Inc., Pueblo, CO

    Committee/Subcommittee: D18.02

    DOI: 10.1520/STP160520170140