Although Caldicot and Severn Tunnel Junction stations are only 3⁄4 mile (1.2 km) apart, Caldicot's growth as a dormitory for the new Llanwern steelworks kept it open in 1964 when other small stations were closed under The Reshaping of British Railways. Severn Tunnel Junction had important roles at this time as the junction for the Severn Tunnel, the large coal marshalling yards and a new diesel depot, replacing the previous steam locomotive depot. Severn Tunnel Junction also serves the village of Rogiet and is where this line merges with the South Wales Main Line through the Severn Tunnel, so it is also a stop on the Cardiff Central-Bristol Temple Meads-Taunton/Penzance service.
On 16 February 1880, a freight train was derailed when it was in collision with a large rock that had fallen onto the line 1.5 miles (2.4 km) south of Chepstow station, Monmouthshire.[3]