Technical Reports

Investigation of Lateral Track Strength and Track Panel Shift Using AAR's Track Loading Vehicle

  • 01
  • Dec
  • 1997
AUTHOR: Dingqing Li, William Shust
KEYWORDS: Track Strength Inspection, In-Motion Tests, Association of American Railroads, Transportation Test Center
ABSTRACT: The Association of American Railroads (AAR) is conducting extensive lateral track strength (track panel shift) tests using the AAR’s Track Loading Vehicle (TLV). The entire test program consists of three phases: (1) demonstration tests, (2) fundamental tests, and (3) off-site tests and is a joint research effort with the Federal Railroad Administration under its Vehicle Track Systems Program. This report covers the first two phases of tests that were conducted on test tracks at the Transportation Technology Center (TTC), Pueblo, Colorado. The main conclusions are given below based on three different types of TLV tests. Stationary TLV panel shift tests have shown that lateral track strength can be measured on intact track with maximum track deflections of 0.3 inch. Among a number of load and track variables examined, vertical axle load and ballast consolidation were shown to have the most significant influence on lateral track strength. Single tie push tests were also performed and support trends as identified by TLV tests. In-motion TLV panel shift tests were conducted using repeated TLV passes over a given test zone. These were used to identify lateral force levels that cause constant deformation growth per vehicle pass, and are defined as the critical lateral load. Critical lateral loads and misalignment growths were determined as a function of vertical axle load, tie type (wood versus concrete) and rail temperature. A technique known as stiffness profile testing has been developed for in-motion track strength measurements. This technique used rail-contacting sensors and two-pass TLV tests to examine strength variation along a track. Weaker locations in track were identified. This technique will be improved in the future, with the goal of single-pass continuous measurement using non-contacting sensors.