On May 19, 2018, at 7:02 a.m. local time, southbound CSX Transportation (CSX) freight train X41518 derailed near milepost (MP) 102.9 as it approached a bridge overpass in Alexandria, Virginia. The train had been traveling on main track one of the RF&P subdivision. As a result of the derailment, the CSX bridge supporting main track one was extensively damaged and collapsed at the approaching abutment wall. The bridge structure and 8 of the 31 derailed railcars fell upon the tracks below, owned by Norfolk Southern Railways (NS). The CSX bridge for main tracks two and three was not involved and remained in service throughout the investigation.
We determined that the probable cause of the CSX Transportation train derailment and subsequent bridge collapse on May 19, 2018, was a subgrade fill failure of the track structure that displaced a large area of ballast under the low rail of the track near milepost CFP 102.9, resulting in a cross-level deviation of the track significant enough to allow a wheel climb derailment.