Switching Ends. Norfolk Southern 6311 and 6332 (SD40E) lead train H53 as it make the trip to Enola, PA over the Susquehanna River on the Rockville Bridge on November 18, 2020. With the introduction of the SD70ACus to the helper fleet in Altoona, PA, these standard cabs have been released to other local assignments across the system, regularly seeing the front of the train for the first time in many years. The Rockville Bridge was completed in 1902 and remains the longest stone masonry arch railroad viaduct in the world.