Changes

Sutton Bridge Junction Signal Box is a currently an operational signal box on Network Rail. It is located approximately 23/3 4 of a mile south of Shrewsbury station, and controls Sutton Bridge Junction. It originally controlled the Severn Valley line's connection with the rest of the network at Shrewsbury, and still controls the junction between the Shrewsbury & Hereford line and the Cambrian line to Machynlleth, Aberystwyth and Pwllheli, and . It also controls access to Coleham yard. It also Yard, and has an Up goods loop, which is the truncated 'Up Avoiding' goods only line which originally ran from Bayston Hill signal box to the south (now closed). The Up direction is towards Shrewsbury for the Cambrian and Hereford lines, whilst Up was to the south on the Severn Valley line.

The box was built in 1913 to replace earlier signalling installations at the junction, and is built to conventional GW style of the time all in brick. However, although because of its location in connection with the Severn Valley line , it has full height windows on the operating floor around the whole northern end, an amendment to the standard design. Originally, it had a nameplate nameplates mounted on both the front facing the mainline and on the rear facing the Shrewsbury & Hereford and Severn Valley linelines respectively, but the rearmost one on the rear's has at some point been removed and its whereabouts is currently unknown. It  The Box has a standard GW design 61 lever 3-bar vertical tappet frame which is , original to the box and is therefore from the date of the same vintageconstruction. Three of the levers retain brass lever leads (the plate indicating the lever's purpose and what levers must be reversed to enable it to be worked), whilst the others all have the later rectangular traffolite style. Interestingly, the original lever leads related to the Severn Valley line referred to 'To' or 'From' Worcester, for example 'From Worcester Safety' for a lever which worked a trap point for any runaway train coming from Berrington.

In the 1960s the Shrewsbury & Hereford line came under the control of the London Midland Region (LMR) of British Railways as far south as Craven Arms, meaning the GWR design box and frame underwent have since then undergone some notable changes. It now has standard BR bakelite block instruments, a LMR style block shelf - which bears LMR style lamp and arm indicators and the modern diagram - and electric lock releases actuated by catch handles on most electrically locked levers, rather than the GWR/BR(W) style block shelf plungers. Most of the test date stickers on the instruments and indicators date from 1966 suggesting the replacement of the shelf and equipment thereon occurred in 1966 or 1967.

The layout of the junction and access to Coleham Yard and other ancillary sidings and loops has over time been extensively remodelled since the late 1960s/70s which has caused many levers to be taken out of or change use. This means for example that lever 5, which was originally the inner home signal reading off the Severn Valley line, is now the Up starting signal and therefore in continuous use.

As part of the significant redesign remodelling of the layout at Sutton Bridgeover time, many of the original GWR/BR(W) design signals were have been replaced with standard BR(LMR) upper quadrant signals, unusually resulting in a GWR box controlling LMS style upper quadrant signals. The Up inner home on the Cambrian branch and the Down home bracket remain GWR/BR(W) lower quadrant design however. On the latter, the space can be made out for the signal that originally controlled the junction onto the Severn Valley line. The box also controls colour light signals in the form of its Up distant signals on both the Hereford and Cambrian lines, and the Up home on the Hereford line is a 3-position colour light, which only shows green when the Up inner home and starting signals are cleared. It will show a yellow when reversed, only once the home berth track circuit immediately in rear of it has occupied, effectively checking the train down to a low speed in accordance with what was (and still is on the SVR) Rule 39(a). The box's down distant signal, mounted beneath Severn Bridge Junction's starting signal, is one of only two remaining working lower quadrant distant signals on Network Rail. The box works to Absolute Block regulations to the north and south, working to Severn Bridge Junction to the north and Dorrington to the south, and Marshbrook when Dorrington is switched out. It works to Machynlleth Signalling Centre under Track Circuit Block regulations as far as the commencement of Cab signalling board on the Cambrian, beyond which the in-cab signalling system European Rail Traffic Management System (ERTMS) comes into effect. Controls on communication between Sutton Bridge and Machynlleth are mounted on the diagram. Unusually for a box of its size, Sutton Bridge Junction has the capacity to switch out and does so on a daily basis, causing Severn Bridge to work to Dorrington or Marshbrook.

The box works to Absolute Block regulations to the north and south, working to Severn Bridge Junction to the north and Dorrington to the south (and Marshbrook when Dorrington is switched out). It works to Machynlleth Signalling Centre under Track Circuit Block regulations as far as the commencement of Cab signalling board on the Cambrian, beyond which the in-cab signalling system European Rail Traffic Management System (ERTMS) comes into effect. Controls on communication between Sutton Bridge and Machynlleth are mounted on the diagram. Unusually for a box of its size, Sutton Bridge Junction has the capacity to switch out and does so on a daily basis. Originally the box worked by Absolute Block to the now closed Coleham and Bayston Hill boxes to the north and south respectively, to Hookagate signal box towards Machynlleth, and to Burnt Mill Junction box on the Severn Valley Line, all by absolute block. HoweverAll of those boxes have now closed, this box closed Burnt Mill in 1937 resulting in Electric Train Token working from Sutton Bridge to Berrington, Coleham and Bayston Hill boxes in the 1960s, and communication Hookagate in the 1980s when Electric Train Token was introduced between Sutton Bridge and Welshpool. This then by gave way to Radio Electric Train Token Block on the Cambrian line, managed from Machynlleth Signal Box, which in turn gave way to Berrington signal boxthe current ERTMS.