Comparison of Ballast Drainage Improvement Between Track Lifting and Shoulder Cleaning Based on CFD Simulations

Railroad track performance largely depends on ballast drainage conditions. Over the years, different ballast maintenance methods have been developed and applied in the field, aiming to restore ballast drainage capability. But the benefits from different maintenance methods have not been well quantified and compared. This study investigates and compares the benefits of the two popular ballast drainage maintenance methods used in North America, shoulder cleaning and track lifting, through numerical simulations based on computational fluid dynamics (CFD). Different fouling conditions are simulated with permeabilities quantified from the field-collected fouled ballast samples to ensure that the numerical models are representative. Because the unit cost of shoulder cleaning and track lifting varies and depends on the specific application conditions, the normalized drainage health index (NDHI) and the normalized drainage restoration ratio (NDRR) are introduced to make fair comparisons and provide unbiased parameters for practitioners to use in the future. Preliminary results from this study indicate shoulder cleaning provides better ballast drainage improvement than track lifting if the unit costs per ballast volume of shoulder cleaning and track lifting are identical.