Document Type

Journal Article

Publication Date


Subject Area

infrastructure - track, infrastructure - vehicle, planning - methods, land use - planning, mode - rail


Vertical track support, Tracks, Track strength degradation, Track loading vehicle, Subgrade (Railroads), Strategies, Strategic planning, Stiffness, Rigidity, Railroad tracks, Railroad ballast, Priorities, Objectives, Nondestructive tests, Nondestructive testing, NDTs, Measuring methods, Maintenance and repair, Maintenance, Goals, Deflection, Ballast (Railroads)


As part of an Association of American Railroads (AAR) research program, the Transportation Technology Center, Inc., a subsidiary of AAR, has developed a new method using its track loading vehicle (TLV) technique to measure vertical track deflections under given vertical loads while in motion. The technique was developed to identify weak track locations and to measure the load-carrying capacity of existing tracks to aid and prioritize track maintenance and to improve railroad operational performance. Discussed are the development and implementation of this continuous vertical track-support measurement technique. This technique provides an in-motion and nondestructive means of testing vertical track support. Currently, this newly developed TLV technique is being used in revenue service to identify large track stiffness variations along the track, indicating lower track strength or abrupt transitional stiffness changes. It is also used to locate the source of lower strength due to ballast and subgrade conditions, as well as to assess the need for upgrades to accommodate higher operation speeds or heavier axle loads. Extensive tests in revenue service have shown this TLV testing technique to be a viable method to perform the above tasks successfully. In addition, this new test technique can be used to improve the understanding of track strength degradation over time and to help direct limited maintenance resources to track locations requiring near-term maintenance.