Current regulations require locations of noncompliant ballast to be remediated within 30 days or to be taken out of service, regardless of track class. In 2013, the Association of American Railroads (AAR) applied for a waiver to the current regulations that proposed a track class specific approach to managing noncompliant ballast. In 2015, the Federal Railroad Administration (FRA) granted the waiver subject to certain conditions including weekly track geometry measurements. The waiver also initiated a research project to investigate the behavior of reduced performance ballast. BNSF Railway (BNSF) operated safely throughout the waiver period on 340 route miles of its Creston and St. Joseph subdivisions from June 12, 2017, to January 31, 2019. Researchers observed a significant variation in track performance at fouled ballast locations—a strong argument for a performance-based rule for managing noncompliant ballast. The results presented in this report are specific to the conditions on the designated waiver territory which was posted as track class 4 and carried over 100 million gross tons (MGT) of traffic per year. Future projects could be conducted on territory with different traffic, weather conditions, and types of fouling materials.