Whitechapel signal cabin

Whitechapel
EN
Overview
Opened	18 November 1951
Closed	6 March 2021
Operator	London Underground

Whitechapel (prefix EN) is a signal cabin located near the station of the same name on the District and Hammersmith & City lines of London Underground 's Sub-Surface Railway (SSR). Since 2009, it ranked amongst some of the smallest operating signal cabins on the Underground network. It closed on 6 March 2021 under the Four Lines Modernisation (4LM) re-signalling programme.

Metropolitan District Railway

Whilst Whitechapel station had been opened in 1869 as part of the East London Railway (ELR) extension from Wapping to Liverpool Street, the first signal box came with the eastward extension of the Metropolitan District Railway (MDR) from Mansion House opening on 6 October 1884. The proliferation of tracks used by the MDR was apparent with the provision of a lever frame of 61 levers. In 1902, the signal box was renamed Whitechapel West due to the splitting of control in the area with Whitechapel East signal box of 49 levers.

In 1907, the two signal boxes at Whitechapel were incorporated into a combined signal box (prefix EN) equipped with a 51-lever Westinghouse 'B-style' electrically interlocked miniature lever frame, similar to the surviving lever frame at Edgware Road (OP) signal cabin.

London Transport

On 18 November 1951, a 37-lever Westinghouse 'N-style' electrically interlocked miniature lever frame replaced the existing one, retaining the same cabin prefix of EN. During this time, Whitechapel signal cabin reached its maximum extent of control with a siding at Whitechapel, four platforms for the District and Metropolitan lines, two platforms at a lower level for the East London Line, Shoreditch station and St. Mary's Curve linking all three lines.

The 1960s saw the advent of concentration of signalling on the London Underground, with Earl's Court control room opening in 1965 and assuming control of the District line west of Tower Hill, the southern half of the Circle line, as well as most of the Piccadilly line.

The success of concentrating signalling control using programme machines with further control rooms, such as Coburg Street (opened 1969), was a pioneering advancement in railway signalling, massively expanding areas of control. Before this, signal cabins were often limited by the size of lever frames over small geographic areas such as termini or diverging junctions. Control rooms featured desks with rows of push-button panels accessible to the signaller should they need to intervene. Under regular running, pre-loaded timetables running via programme machines could set signals and points automatically with little human input, massively expanding capabilities.

Signal concentration schemes continued into the early 2000s with Baker Street Service Control Centre (SSR) replacing numerous signal cabins between Stanmore, Baker Street and Aldgate. However, broader financial difficulties in the statutory bodies overseeing London's Transport network meant the full benefits of signal concentration were never realised. As a result, signal concentration on the SSR would remain substantially incomplete, with several signal cabins, such as Whitechapel, continuing to operate into the 21^st century.

Present Day

The rationalisation of the area controlled by Whitechapel signal cabin started in 1998, with control of the East London Line passing to the New Cross Signalling Equipment Room (SER) on 24 March 1998. December 2007 saw the closure of the East London Line for major rebuilding works in preparation for the reincarnation of the route as part of the London Overground network. St. Mary's Curve, the double-track connection used to supply the East London Line with rolling stock during London Underground ownership, was removed during this time.

Work on the four high-level platforms at Whitechapel began in 2009 to rebuild the station for the Crossrail project. The stabling siding was removed, and the inner two tracks were abolished to create a large island platform and circulating area flanked in two ways with a trailing crossover in each direction for flexibility during service disruption. Due to the loss of two platforms at Whitechapel, Hammersmith & City line services were extended to run to Barking all day, having previously only done so during peak times. From a peak of 47 levers in use in 1990, just 13 remained operable after 2011.

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 was split into 14 Signal Migration Areas (SMA), of which Whitechapel lay in SMA 3 concerning the railway between Euston Square, Monument and Stepney Green. Following intensive testing and a series of aborted go-live dates, the Whitechapel signal cabin closed after traffic in the early hours of 6 March 2021, ending almost 70 years of operation. SMA 3 was subsequently pressed into revenue-earning service the following day.