Other Reports

Task Force Report: Rail Failure Evaluation

  • 01
  • May
  • 1984
AUTHOR: Transportation Systems Center
SUBJECT: Accident Investigations, Evaluation
KEYWORDS: Passenger Rail, Rail Fracture, Alloy Rail
ABSTRACT: [From the Executive Summary] On November 12, 1983, an Amtrak passenger train operating on Missouri Pacific track in the vicinity of Marshall, Texas, derailed at a speed of between 70 and 75 miles per hour as it traversed a temporary track repair. The alloy rail over which the train was passing fractured and concurrently fragmented into a number of relatively small pieces. The extended length of the fracture and the concurrent fragmentation are not consistent with past experience. Similar fractures observed in standard, plain carbon steel rail generally have characteristic lengths about one third of the fracture length in the subject alloy rail, and do not exhibit fragmentation. Alloy rails of the type involved in the Marshall, Texas, derailment constitute a very small fraction of the existing domestic rail population. However, alloy rail is being used increasingly on domestic railroads because of its improved wear characteristics. As a result of the unusual failure mode, and because of the increasing domestic usage of alloy steel to reduce rail wear, the Federal Railroad Administration requested that the Transportation Systems Center (TSC) form a Task Force to conduct a technical evaluation of the subject rail failure. The purposes of the technical evaluation were to: identify the technical factors involved in the subject rail failure; assess the safety risks, if any, associated with similar alloy rail installations; and identify measures which may be used to reduce any such risks. Based on its technical evaluation, the Task Force has found that the subject rail fracture originated at a torch-cut notch in the rail end. The fracture was a sudden, single event which was probably initiated by the impulsive overload of a lead locomotive wheel striking a rail height mismatch at high speed. The unusual extent of the fracture is believed to have resulted from adverse residual stresses existing in the subject rail.