FIELD EXPERIENCE AND ACADEMIC INQUIRY TO UNDERSTAND MECHANISMS OF SPIKE AND SCREW FAILURES IN RAILROAD FASTENING SYSTEMS

摘要

Since 2000, at least 10 derailments on four different North American railroads have been caused by broken spikes (or screws) that resulted in wide gage. The broken spikes and screws discovered following these derailments, and those found in routine track inspections, are most often found in elastic fastening systems on timber crossties. The depth of spike failure- about 1.5 inches beneath the top of the crosstie- is remarkably consistent and makes detection through visual inspection difficult. In their early stage, broken spikes can exist in track meeting all track geometry safety standards. Broken spikes and screws represent a risk to train operations and increase life-cycle costs through labor-intensive inspections and premature component replacement. A project at the University of Illinois funded by the Federal Railroad Administration with close Class I partnership is examining the root cause of this problem. This paper describes the maintenance and inspection challenges associated with broken spikes, as well as the academic work at the University of Illinois to build hypotheses related to the causes of broken spikes. A literature review and a series of field inspections were conducted to better understand this problem. A set of hypotheses to understand spike failure was then constructed based off these observations. Two major findings are that longitudinal load transfer through elastic fasteners is a driving factor and that spike breakage is primarily a mechanism problem and not a material problem.