Severn Bridge Junction is the area of railway lines just south east of

Shrewsbury railway station Shrewsbury railway station is in Shrewsbury, Shropshire, England. Built in 1848, it was designated a grade II listed building in 1969. The station is north west of Birmingham New Street. Many services starting at or passing through the stati ...

, in

Shropshire Shropshire (; alternatively Salop; abbreviated in print only as Shrops; demonym Salopian ) is a landlocked historic county in the West Midlands region of England. It is bordered by Wales to the west and the English counties of Cheshire to th ...

England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...

. It is controlled by a mechanical interlocked

signal box In signal processing, a signal is a function that conveys information about a phenomenon. Any quantity that can vary over space or time can be used as a signal to share messages between observers. The ''IEEE Transactions on Signal Processing'' ...

of the same name, which is the largest operational mechanical signal box in the world.Network Rail
Refurb of World's largest working mechanical signal box completes The

Network Rail Network Rail Limited is the owner (via its subsidiary Network Rail Infrastructure Limited, which was known as Railtrack plc before 2002) and infrastructure manager of most of the railway network in Great Britain. Network Rail is an "arm's leng ...

signalling area code is 'SBJ.'

Background

The complexity of the railway system in the area is brought about by the convergence of five major lines at , built in the

Victorian era In the history of the United Kingdom and the British Empire, the Victorian era was the period of Queen Victoria's reign, from 20 June 1837 until her death on 22 January 1901. The era followed the Georgian period and preceded the Edwardia ...

by two competing and yet also co-operating railway companies, the

Great Western Railway The Great Western Railway (GWR) was a British railway company that linked London with the southwest, west and West Midlands of England and most of Wales. It was founded in 1833, received its enabling Act of Parliament on 31 August 1835 and ran ...

and the

London and North Western Railway The London and North Western Railway (LNWR, L&NWR) was a British railway company between 1846 and 1922. In the late 19th century, the L&NWR was the largest joint stock company in the United Kingdom. In 1923, it became a constituent of the Lo ...

. They were competing to connect the coal and raw material supplies of South Wales with the industrialised Midlands and Northwest; and secondly to transport passengers to and from London to the port of Liverpool. After the GWR amalgamated with the

Cambrian Railways The Cambrian Railways owned of track over a large area of mid Wales. The system was an amalgamation of a number of railways that were incorporated in 1864, 1865 and 1904. The Cambrian connected with two larger railways with connections to the ...

in 1921, it was also a major point of accessing GWR services into Mid and West Wales: *

Cambrian Line The Cambrian Line ( cy, Llinell y Cambrian), also known as the Cambrian Main Line ( cy, Prif Linell y Cambrian) and Cambrian Coast Line ( cy, Llinell Arfordir y Cambrian), is a railway line that runs from Shrewsbury, England, westwards to Aber ...

(GWR) *

Shrewsbury to Chester Line Shrewsbury ( , also ) is a market town, civil parish, and the county town of Shropshire, England, on the River Severn, north-west of London; at the 2021 census, it had a population of 76,782. The town's name can be pronounced as either 'Sh ...

(GWR) *

Wolverhampton to Shrewsbury Line Wolverhampton () is a city, metropolitan borough and administrative centre in the West Midlands, England. The population size has increased by 5.7%, from around 249,500 in 2011 to 263,700 in 2021. People from the city are called "Wulfrunian ...

(GWR) * Welsh Marches Line: **North to via

Crewe and Shrewsbury Railway The Crewe and Shrewsbury Railway was a railway company which was previously owned by the London and North Western Railway (LNWR), built to connect Crewe with the Shrewsbury and Hereford Railway which was jointly owned with GWR. Authorised in 1 ...

(LNWR) **South to via

Shrewsbury and Hereford Railway The Shrewsbury and Hereford Railway was an English railway company that built a standard gauge line between those places. It opened its main line in 1853. Its natural ally seemed to be the Great Western Railway. With other lines it formed a rou ...

(Joint) Lines formerly converging in the area also include the regionally important

Severn Valley Railway The Severn Valley Railway is a heritage railway in Shropshire and Worcestershire, England. The heritage line runs along the Severn Valley from Bridgnorth to Kidderminster, following the course of the River Severn for much of its route, and c ...

(GWR), and the

Stafford to Shrewsbury Line Stafford () is a market town and the county town of Staffordshire, in the West Midlands region of England. It lies about north of Wolverhampton, south of Stoke-on-Trent and northwest of Birmingham. The town had a population of 70,145 in the ...

(LNWR).

Junction

The railway junction lies directly south of the railway station. It was constructed jointly by the GWR/LNWR after the completion of improvements to their jointly owned

, which at this location junctioned with the

. To allow freight trains to move to/from South Wales direct to the Midlands and hence avoid the passenger railway station, the junction was constructed in a tight triangular form south of the

River Severn , name_etymology = , image = SevernFromCastleCB.JPG , image_size = 288 , image_caption = The river seen from Shrewsbury Castle , map = RiverSevernMap.jpg , map_size = 288 , map_c ...

Signal box

Jointly constructed from 1902 to an enlarged standard LNWR design of 1876, the three storey structure is built of two storeys of red brick and cement, with a third floor mainly of wooden weather board pin-panel containing the glass windows, all topped by a

Welsh slate The existence of a slate industry in Wales is attested since the Roman period, when slate was used to roof the fort at Segontium, now Caernarfon. The slate industry grew slowly until the early 18th century, then expanded rapidly until the l ...

pitched roof. Access is via a door on the rear, with the lower two floors housing interlocking signalling equipment accessed via two internal wooden staircases. The main operational floor houses a 180 lever interlocked frame, divided into two sections: Abbey Foregate to Sutton Bridge; Shrewsbury station to Crewe Junction. The frame scale makes it the largest remaining mechanical signal box on the British network, and from 2011 it became the largest mechanical signalbox in the world, following the closure of the 191 lever box at

Spencer Street Spencer Street is a major street and thoroughfare in the Melbourne central business district, central business district of Melbourne, Victoria (Australia), Victoria. The street was gazetted in 1837 as the westernmost boundary of the Hoddle Grid. ...

Melbourne, Australia Melbourne ( ; Boonwurrung/Woiwurrung: ''Narrm'' or ''Naarm'') is the capital and most populous city of the Australian state of Victoria, and the second-most populous city in both Australia and Oceania. Its name generally refers to a metropol ...

. Today only approximately half of the levers are in operational use, although it still takes two signallers to operate the complete system on a 24/7 basis, allowing 300 train movements per day. The signal box is a

grade II listed building In the United Kingdom, a listed building or listed structure is one that has been placed on one of the four statutory lists maintained by Historic England in England, Historic Environment Scotland in Scotland, in Wales, and the Northern Irel ...

and underwent extensive heritage renovation in 2020-21, carried out by Network Rail.

Future

Although there have been line closures in the Shrewsbury area, and the closure of the joint

motive power depot The motive power depot (MPD) or locomotive depot, or traction maintenance depot (TMD), is the place where locomotives are usually housed, repaired and maintained when not being used. They were originally known as "running sheds", "engine shed ...

at the end of the steam era in the 1960s, there is still a complex residual converging rail system in the area. Within of the junction, there are another three interlocked mechanical signal boxes: *Abbey Foregate Junction: located on the Wolverhampton line to allow access to the adjacent Abbey Foregate yard; its code is 'AF'. *Crewe Junction: located on the north side of the station, at the convergence of the lines from Crewe and Wrexham; its code is 'CJ'. *Sutton Bridge Junction: located south of English Bridge Junction, at the convergence of the line to Hereford and the Cambrian Line; its code is 'SUB'. A further three boxes that had formed part of the local system: *Crewe Bank: closed 8 December 2012. *English Bridge: controlled the southside of the triangular junction through Coleham to Sutton Bridge Junction. Closed in 1953, its controls were transferred to Severn Bridge. *Harlescott Crossing: closed 8 December 2012. Network Rail currently believes that to simplify this system to allow it to be remotely controlled through colour-light signals would not be economical. Hence the current mechanical signalling system in the area is presently envisaged to remain in operation until at least 2030, and possibly as long as 2050 on current plans.Railway Herald
Issue 295, p8

Background

Junction

Signal box

Future

See also

References

Further reading