|Type||Suburban rail, Heavy rail|
|Locale||South East Wales, Severn Estuary, Monmouthshire, Gloucestershire|
|Stations||6 (14 disused)|
|Operator(s)||Transport for Wales|
First Great Western
|Rolling stock||Class 43 HST|
Class 142 "Pacer"
Class 143 "Pacer"
Class 150 "Sprinter"
Class 158 "Express Sprinter"
Class 170 "Turbostar"
Class 175 "Coradia"
|Track gauge||1,435 mm (4 ft 8 1⁄2 in) standard gauge|
The places served by the route are:
- Connection with Dean Forest Railway
- Severn Tunnel Junction located in Rogiet
Local passenger services are currently provided by Transport for Wales, with an approximately hourly service in each direction on the Cheltenham Spa to Maesteg service. These are supplemented by CrossCountry services between Cardiff Central and Nottingham, which serve Gloucester and Newport, serving either Lydney or Chepstow then fast to Newport for example. The intermediate stations are omitted except during the early morning and late evening.
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-Portsmouth Harbour service.
In 1977 the Parliamentary Select Committee on Nationalised Industries recommended considering electrification of more of Britain's rail network, and by 1979 BR presented a range of options to do so by 2000. Options included electrifying numerous former Great Western routes including the Gloucester to Newport line. Under the 1979–90 Conservative governments that succeeded the 1976–79 Labour government the proposal was not implemented.