The railway line through Caldicot was built as the broad gauge South Wales Railway in 1850, although the nearest station was at Portskewett, two miles to the east.
In 1861 a private siding was opened to serve the Caldicot Iron & Wire Works, from 1880 the Severn Tinplate Works, on what is now the industrial estate on the Sudbrook road, south of the castle.
In typical broad gauge fashion, these works lines used two short hand-worked turntables to move wagons between the lines, rather than points.

In 1872, the South Wales Railway was re-gauged from broad gauge to standard gauge.
By 1875 the wire works was also served by a level crossing and a crossover between the two running lines, controlled by a signal box.
It is likely that this relaying was carried out earlier, as part of the re-gauging work.

In 1878, a branch line was laid to Sudbrook, to support the works for construction of the new Severn Tunnel.
One of the main tasks of this line was to deliver coal for the pumping engines needed to drain the tunnel workings.
Even after the long-delayed tunnel opened in 1886, on the South Wales Main Line, this coal traffic remained the major reason for keeping this branch in service.
By 1925, the busier traffic on the main line had led to an expansion of the junction with a head siding.
Further sidings were provided to the north of the running lines, on the town side.
These were well to the east of where the station is today.

Caldicot station opened as a passenger halt on 12 September 1932.
The road serving the station had been here for many years beforehand, since the building of the tunnel.
It crosses the low tunnel line by an overbridge, then passes under the Gloucester line by an unusually low underpass.
This underpass was originally provided to give farm access to the land of the Caldicot Levels south of the railway and it is a mark of the passenger station's minor importance that such a restricted access continues to this day.

In 1939, construction began on the Royal Navy Propellant Factory, Caerwent.
A second branch was laid from Caldicot, this time to the north east.
The private siding agreements are first made in the name of the builders McAlpine, then the United States Army Air Forces from 1943, and only transferred to the Ministry of Defence as the Royal Navy in 1944.
To support the increased traffic, a second crossover was constructed, together with a loop siding on the Down line.

Although production at the propellant factory ceased in the 1960s, it remained an important storage depot for munitions until 1993.
The branch remains in service to this day, although little used and mostly just as a storage area for railway vehicles awaiting scrapping.
Most military use of the site, now as a training area, is handled by road, not rail.

The original tinplate works sidings and the sidings serving the town were also taken out of use in the 1960s.
Owing to later building work, no trace remains.
The Sudbrook branch remains, although it is overgrown and no longer immediately usable.
The railway line through Caldicot was built as the broad gauge South Wales Railway in 1850, although the nearest station was at Portskewett, two miles to the east. In 1861 a private siding was opened to serve the Caldicot Iron & Wire Works, from 1880 the Severn Tinplate Works, on what is now the industrial estate on the Sudbrook road, south of the castle. In typical broad gauge fashion, these works lines used two short hand-worked turntables to move wagons between the lines, rather than points.
In 1872, the South Wales Railway was re-gauged from broad gauge to standard gauge. By 1875 the wire works was also served by a level crossing and a crossover between the two running lines, controlled by a signal box. It is likely that this relaying was carried out earlier, as part of the re-gauging work.
In 1878, a branch line was laid to Sudbrook, to support the works for construction of the new Severn Tunnel. One of the main tasks of this line was to deliver coal for the pumping engines needed to drain the tunnel workings. Even after the long-delayed tunnel opened in 1886, on the South Wales Main Line, this coal traffic remained the major reason for keeping this branch in service. By 1925, the busier traffic on the main line had led to an expansion of the junction with a head siding. Further sidings were provided to the north of the running lines, on the town side. These were well to the east of where the station is today.
Caldicot station opened as a passenger halt on 12 September 1932. The road serving the station had been here for many years beforehand, since the building of the tunnel. It crosses the low tunnel line by an overbridge, then passes under the Gloucester line by an unusually low underpass. This underpass was originally provided to give farm access to the land of the Caldicot Levels south of the railway and it is a mark of the passenger station's minor importance that such a restricted access continues to this day.
In 1939, construction began on the Royal Navy Propellant Factory, Caerwent. A second branch was laid from Caldicot, this time to the north east. The private siding agreements are first made in the name of the builders McAlpine, then the United States Army Air Forces from 1943, and only transferred to the Ministry of Defence as the Royal Navy in 1944. To support the increased traffic, a second crossover was constructed, together with a loop siding on the Down line.
Although production at the propellant factory ceased in the 1960s, it remained an important storage depot for munitions until 1993. The branch remains in service to this day, although little used and mostly just as a storage area for railway vehicles awaiting scrapping. Most military use of the site, now as a training area, is handled by road, not rail.
The original tinplate works sidings and the sidings serving the town were also taken out of use in the 1960s. Owing to later building work, no trace remains. The Sudbrook branch remains, although it is overgrown and no longer immediately usable.
Caldicot railway station