Track Support Measurements for Improved Resiliency of Railway Infrastructure

Abstract

Track support is necessary for reliable, resilient railroad track infrastructure. Ability to recover quickly from adversity is a hallmark of the railway industry, and ability to rapidly restore track to service is a main element contributing to resilience of rail service. Poor track support conditions can increase dynamic and impact loading on track superstructure components that can accelerate deterioration of track components, potentially inhibiting the resilience of railroad track. As track components deteriorate or material properties continue to degrade in an area, affected ties become poorly supported and shed their load to better-supported ties. Various problems develop owing to increased tie load, rail stress, and ballast stress, leading to ballast degradation and track or tie vibrations. These problems can be avoided if proper track support is uniformly provided so that no area is overstressed. Several measurement techniques are discussed for evaluating track support: modulus and transient displacements, including track deflection techniques, video cameras, accelerometers, spectral analysis of surface waves for assessment of sublayer moduli, and falling weight deflectometer for deflection and basin analyses. These measurement techniques are compared and contrasted, are illustrated by using a track bearing capacity example, and are demonstrated as useful in assessing tie and track support problems with the goal of improving inspection and maintenance at problem locations. Data from these tests can be useful in designing track and maintenance plans to avoid track support failures, a necessary step to ensure track infrastructure resiliency.