CSX operates a former Richmond Fredericksburg & Potomac branch east from Dahlgren Junction (just north of Fredericksburg) to just east of Sealston. There are a couple of freight customers near Sealston; this line is north of and parallel to VA Route 3.
East of Sealston the branch was operated by the US Government (US Navy) to support the Dahlgren Laboratory on the western bank of the Potomac River. The US Navy segment has been abandoned for some time, and land in the area is posted "No Trespassing".