As part of continuing research into mud pumping and fine-filled ballast, the Federal Railroad Administration and the Association of American Railroads studied how moisture in fine-filled ballast can affect track performance. The goals of this research were to better identify problematic locations and recommend more effective maintenance practices. Transportation Technology Center, Inc. (TTCI) completed the first phase of testing in June 2019. The objective of Phase I was to quantify how moisture can increase track settlement (up to 15 times that of dry) and reduce the track modulus and drainage capabilities of the ballast section. In cases where the water source is from rainfall, “Rainy Section” testing identified several inches around the tie as the problematic region. Based on this study, mud pumping maintenance and remediation efforts should focus on drainage of this region.