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SIGNALLING/TELECOMS
CLIVE KESSELL
Fond farewell
to a favourite power box
HRH The Duke of Edinburgh visits the new London Bridge power signal box in 1976.
T
he huge modernisation of railway signalling in the UK during the 1960/70s and early 1980s came about through the introduction of Power Signal Boxes (PSB), with many covering significant miles of route. All the BR regions had them and, by the time of the last introduction, most of the trunk routes had been re-signalled, offering big increases in capacity by means of continuous track circuit block sections, as well as an element of centralised control.
However, these PSBs are now coming to the end of their economic life, being replaced by the Rail Operating Centres (ROCs). The Southern Region was no exception and had a plan to cover its entire geographic area with 13 PSBs. The first and second of these were at Dartford and Feltham, but the third, and by far the biggest, was at London Bridge. This area had been signalled in the 1920s with individual signal boxes at all the major locations, including the notorious Borough Market Junction, where the lines to Charing Cross and Cannon Street diverged. With the heavy and increasing suburban traffic, an urgent need existed to make permanent way alterations and centralise the signalling. So came about the London Bridge Power Box, opened in stages during the period 1975/6 with due ceremony, the Duke of Edinburgh being the guest of honour. The box has been in service for 45 years but, in recent years, much of its operating area has been transferred to the ROC at Three Bridges. The summer of 2020 saw the very last area of control at Hither Green transferred, and so ended a remarkable period of operation that had transformed the railway service in SE London. This article traces the technology of the London Bridge box and the innovative additions that were state of the art at that time.
Rail Engineer | Issue 186 | September/October 2020
London Bridge area The Southern had three divisional areas, SE, Central and SW. The latter was pretty much self-contained, but the South East and Central came together at a number of London terminals, London Bridge being one of them. The new PSB had to span these boundaries, so integrating the management aspects was part of the project.
