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ICTD 2026

Rail Transport

Advances in Track Structure Evaluation

Effect of Missing Ties on Track Modulus: A Mechanistic Evaluation

Tuesday, June 30, 2026
3:45 PM - 4:00 PM East Coast USA Time
Abstract: The structural performance and serviceability of railroad tracks are highly dependent on the mechanical behavior of their substructure. Track modulus, which characterizes the load-deflection response of the track system, serves as a key mechanistic indicator of support condition and track health. Conventional inspection methods rely largely on empirical assessments that fail to fully capture the complex interaction between track components.
This study presents a mechanistic investigation into the effect of missing ties on track modulus. A three-dimensional finite element model of a ballasted track segment was developed in ABAQUS to simulate the track’s response under varying tie configurations. The model incorporated linear elastic material properties for rail, ties, ballast, sub-ballast, and subgrade layers. A series of parametric analyses was conducted to systematically assess how varying the number of consecutive missing ties influences load distribution along the rail and the resulting vertical deflection response.
Results indicate that the loss of ties significantly reduces track modulus, with reductions of up to 75% observed in cases with three consecutive missing ties. As the number of missed ties increases, the track’s capacity to carry and distribute loads deteriorates further, underscoring the critical role of ties in maintaining rail stability. The findings from this study provide a mechanistic framework for quantifying support degradation due to missing ties and inform the development of robust track evaluation and maintenance strategies.

Learning Objectives:

Attendees can expect to learn the following from this session:
  • Understanding the role of track modulus as a mechanistic indicator of railroad track support condition and health.
  • Analyzing how varying configurations of missing ties affect load distribution and rail deflection in ballasted track systems using finite element modeling.
  • Applying mechanistic insights to quantify the degradation of track support caused by missing ties and develop improved strategies for track evaluation and maintenance.