Sutton Bridge Junction Signal Box
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See also Sutton Bridge Junction.
Sutton Bridge Junction Signal Box is a currently operational signal box on Network Rail. It is located approximately 2/3 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 access to Coleham yard. It also 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, 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 mounted on both the front facing the mainline and on the rear facing the Severn Valley line, but the one on the rear's whereabouts is currently unknown. It has a 61 lever 3-bar vertical tappet frame which is original to the box and is therefore of the same vintage. 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.
The box is built on the eastern side of the Shrewsbury & Hereford line (sometimes in conjunction with the Hereford and Newport referred to as the North & West), and originally the SVR joined this line immediately to the north of the box, coming in from the southeast. The junction and where the line passed under a road bridge can still be readily seen. Until 1988, a stub of the Severn Valley line remained in use, providing via a reverse move access to the site of Shrewsbury Abbey station (Shropshire & Montgomeryshire Light Railway), which remained in use as a fuel terminal.
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 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.
The layout of the junction has 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.
The box was thoroughly measured in the 1980s by an SVR volunteer to ensure accuracy in the plans for Kidderminster Station signal box.
Current published plans indicate the box will be closed in 2025 with its area of control passed to Cardiff Rail Operating Centre (ROC), although it remains to be seen if this target will be achieved.
Signalling diagram
Signalling controlled from the box
As part of the significant redesign of the layout at Sutton Bridge, many of the original GWR/BR(W) design signals were replaced with standard BR(LMR) upper quadrant signals, unusually resulting in a GWR box controlling LMS style 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. 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. However, this box closed in 1937 and communication was then by Electric Train Token to Berrington signal box.