Wood Tie Fastener Performance Requirements: The User’s Point of View


The wood tie/cut spike fastener system has been in use on North American railroads since the 19th century (2). However, as the nature of the railroad-operating environment has changed over the last decade, there has been an increasing emphasis on long heavy trains with high axle loading. This has placed a severe burden on the ability of the traditional wood tie-cut spike system to perform its critical functions, particularly on the most severely loaded track locations, such as high curvature and heavy grade territory. In some cases, this traditional wood tie/cut spike system has proven to be inadequate. Furthermore, this trend towards increased axle loads is continuing, as the industry looks to heavier 286,000 lb. and 315,000 lb. cars in the near future. As this increase in railroad loading continues to place an increasingly severe burden on the traditional cut spike fastener system, the very nature of the cut spike system has been examined from the point of view as to whether this system, or its individual components are appropriate for these heavy-duty load environments. This is particularly true since the failure mechanisms, associated with these severe track locations, appear to be more closely associated with the fastening system (i.e., the cut spikes), than with the wood tie itself. In fact, the basis properties of the wood tie, such as its natural resiliency and electrical isolation, appear to be quite desirable in the heavy duty-loading environment. This, in turn, suggests that the basic wood tie could function in even the most severe environment, provided that an appropriate fastener, or even more effectively, an appropriate tie/fastener system, is utilized. The “elastic track fastener” appears to represent such an improved fastening system. This paper will attempt to define the performance requirements for such an elastic fastener system intended for use in a severe railroad environment.