Technology Digests / Lateral Track Strength Variations at FAST®

TD26-015

Date Posted: July 22, 2026
Authors
  • Stephen Wilk
  • Yin Gao
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Key Findings

  • Despite similar track construction and materials, the STPT testing at FAST showed a significant variation in LTS that ranged from 500 to 3,200 pounds. Revenue service track with a wider range of track types and conditions would be anticipated to have an even greater LTS variation.
  • The LTS variation measured at FAST is great enough that the track could potentially be categorized into different buckle-risks if a reliable LTS measurement technique becomes available.
  • Track movements (e.g., curve breathing) or routine disruptions (e.g., reoccurring tamping, etc.) may be an indicator of weaker track. More reliable methods for categorizing stronger track are needed.
  • The primary proposed STPT performance metric threshold is 1,000 pounds, where the track movement (and buckling) risk is higher when LTS is below that value.

Lateral Track Strength Variations at FAST®

MxV Rail conducted multiple Single Tie Push Tests (STPTs) at the Facility for Accelerated Service Testing (FAST®) throughout 2025 to better understand the variation in lateral track strength (LTS) at FAST and help define performance metrics. Most LTS testing performed previously specifically isolated one or two variables (e.g., tonnage) within a uniform track section.1,2 The latest round of testing, presented in this Technology Digest, focuses on the range of lateral tie resistances observed at FAST and better defines the multiple variables that influence LTS. A more comprehensive overview of LTS variation along the FAST loop provides MxV Rail with a better understanding of FAST track performance, the ability to relate measured LTS to performance metrics, and assistance in indirectly estimating LTS using track-based vision systems. LATERAL TRACK STRENGTH MEASUREMENTS Defined as the resistance to lateral track movement provided by the tie/ballast interface, LTS plays a key role in track buckle…