Technology Digests / Spike Loading Environment in Various Wood Tie Fastening Systems

TD22-016

July 1, 2022
Authors
  • Yin Gao
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Key Findings

  • Of the four systems tested, elastic fastener plates without rail anchors had the highest average peak-to-peak strains for the spikes, creating a higher potential for spike breakage.
  • Both elastic fastener plates with rail anchors and curve block plates had spike bending strains above the fatigue limit. However, the strain levels were lower compared to the elastic fastener plates without rail anchors, offering less potential for spike breakage.
  • Based on the strain level in this test, the spikes in the curve block plates had higher average strains than those in the elastic fastener plates with rail anchors.
  • The spikes in the AREMA plates experienced the smallest strain level and had little strain above the fatigue limit.
  • These test zones need to continue to be monitored to evaluate the effectiveness on remediating spike breakage.

Spike Loading Environment in Various Wood Tie Fastening Systems

Since 2017, MxV Rail (formerly TTCI) has been investigating the issue of spike breakage of elastic fastening systems on Class I railroads, especially in high-degree curve territories. With MxV Rails’ successful development and deployment of instrumented spikes, engineers conducted field experiments to investigate the spike loading environment at the Facility for Accelerated Service Testing (FAST®) in Pueblo, CO. Past research indicated that cut spikes in elastic fastening systems could experience a load level higher than the fatigue limit of the spike material. In this study, the spike loading environment was quantified for various wood tie fastening systems including two potential remediation measures for broken spikes. The test was conducted on a 6-degree curve in a heavy axle loading environment at FAST®. Four common wood tie fastening systems were instrumented with strain-gaged spikes to evaluate real-time dynamic bending strains in cut spikes. The test showed that the spikes used on elastic…