Upminster signal cabin

Upminster
FM
Overview
Opened	20 November 1958
Closed	18 March 2023
Operator	London Underground

Upminster (prefix FM) is a signal cabin located near the station of the same name on the London Underground's District line as part of the Sub-Surface Railway. In its final years, Upminster ranked amongst the smallest signal cabins on the London Underground network. Opened in 1958, it closed in 2023 as part of the Four Lines Modernisation (4LM) re-signalling programme.

It is not to be confused with the Network Rail Integrated Electronic Control Centre (IECC) overseeing the North London Line and London, Tilbury and Southend routes, also located at Upminster.

History

Whilst the District Railway had been serving Upminster since 1932, it was through a shared running agreement using infrastructure and stations managed by first by the London Midland & Scottish Railway (LMS) up until 1948 and then by the Eastern region of British Railways (BR). It took until 1969 for most of the stations and infrastructure between Whitechapel and Upminster to be fully incorporated into London Transport.

The current signal cabin opened on 20 November 1958 and is equipped with a Westinghouse push-button desk. The desk controlled a single Interlocking Machine Room (IMR) fitted with a V-style frame remotely operated by compressed air in response to the signaller setting signals and points via the push button desk. As with all IMRs, the air supply could be isolated and worked manually in case of failure.

The signal cabin itself was timed to be brought into operation in conjunction with Upminster Depot, a stabling and maintenance facility built to compensate for the closure of East Ham Depot. On 13 November 1960, Upminster signal cabin reached its final extent of control with the addition of an Interlocking Machine Room (IMR) at Hornchurch, replacing an LMS signal box dating from 1930.

Signal concentration

Westinghouse's implementation of push-button desks marked the final chapter of the development of signal cabin design and operation on the Underground. Modifications to existing signal cabins, many of which contained substantial lever frames, would often entail partial or wholesale conversion to push button operation with signal cabins at Harrow-on-the-Hill (JB) and Rayners Lane (JP) being notable examples.

In 1962, Earl's Court control room opened, absorbing control of most of the District line west of Aldgate East. The use of programme machines to automatically set signals and points based on a preloaded timetable dispensed with the need for signal cabins, which previously had been required at most diverging junctions or termini locations such as Upminster. Whilst the signal concentration schemes on the District and Northern lines had been successful, the significant capital costs of such projects, coupled with the financial insecurities that London Transport endured through various governmental changes, meant that the full scale of this ambition was never realised. As a result, signal cabins remained in large numbers into the 21^st century.

Four Lines Modernisation (4LM)

The introduction of the S8 and S7 stocks between 2010 and 2015 proved the catalyst for wholesale re-signalling of the SSR. Bombardier, manufacturers of the S stock trains, were also contracted to replace the legacy fixed-block signalling with Distance To Go Radio (DTGR), a form of Automatic Train Operation (ATO). The re-signalling was known as the Sub-Surface Upgrade Programme (SSUG). However, Bombardier's inexperience in delivering signalling systems soon started to drag the SSUG behind schedule and faced mounting costs and delays. London Underground terminated the contract in 2013 at an estimated cost of £900m and a completion date delay of five years.

Thales won the re-tendered contract for SSR re-signalling in 2015, renamed Four Lines Modernisation (4LM). Thales would introduce Communications Base Train Control (CBTC), a variant of SelTrac ATO. Migration to ATO on the SSR is split into 14 Signal Migration Areas (SMA), of which Upminster lies in SMA 7 concerning the railway between Becontree and Upminster. Following extensive testing, the Upminster signal closed on 18 March 2023 upon the commissioning of SMA 7.