Technical Reports

Fundamental Track Gage Widening Tests Using the Track Loading Vehicle

  • 01
  • Jun
  • 1994
AUTHOR: W. P. O'Donnell, A. B. Hazell, Semih Kalay
SUBJECT: Facilities & Test Equipment
KEYWORDS: Wheel Drop Derailments, Derailment Criteria, Rail Rollover, Lateral Load Severity, Projected Load Gage, Extrapolation Factors, Lateral Track Strength
ABSTRACT: In early 1991, a series of fundamental track gage widening tests were conducted at the Transportation Test Center. Tests, using the Track Loading Vehicle (TLV), were performed to provide fundamental knowledge about the manner in which wheel drop derailments occur, to establish data about current rail and track quality, to test and validate various derailment criteria, and to provide a means for the continued measurement of these criteria. The track gage strength characterization tests showed that the initial lateral rail deflection comes in the form of rail translation, twist, and bending. When the lateral load applied at the rail head exceeds the frictional force, the rail slides on the tie plate until the rail base contacts the tie plate shoulder. The critical load levels needed to start rolling the rail are defined by the wheel-rail contact geometry. Resistance to this rail roll motion is obtained from the torsional resistance of the rail and the pullout resistance of the gage spikes. Recent contributions to the prediction of gage widening derailment include the development of criteria and the, formulation of indices to quantify the gage widening behavior of the track. A comprehensive series of tests was performed to validate various track gage widening derailment criteria such as rail rollover, lateral load severity, and projected loaded gage (gage reserve index), as well as to develop new criteria.