in 1848, the Virginia and Tennessee Railroad was not completed southwest of Ingles Ferry (Radford) - and there was no city of Roanoke yet
Source: Library of Congress, A map of the internal improvements of Virginia (Claudius Crozet, 1848)
The Virginia & Tennessee Railroad between Lynchburg and Bristol linked Southwest Virginia to Tidewater prior to the Civil War. The economic connection led to an expansion of slavery in that region west of the Blue Ridge, and shaped the location of the boundary of West Virginia in 1863.
In 1870, William Mahone arranged the merger with the Norfolk and Petersburg Railroad and the South Side Railroad to create the Atlantic Mississippi & Ohio Railroad. That created a single line which connected Bristol to Norfolk.1
Later mergers incorporated it into the Norfolk and Western Railroad, then into today's Norfolk Southern Railroad.