Rayners Lane signal cabin

Rayners Lane
MP
Overview
Opened	20 October 1935
Operator	London Underground

Rayners Lane (prefix MP) is a signal cabin located near the station of the same name on the Uxbridge branch of the London Underground's Metropolitan and Piccadilly lines. It is scheduled to be the last signal cabin operated by London Underground closing under the Four Lines Modernisation (4LM) re-signalling programme.

Metropolitan Railway

The railway in this area opened on 4 July 1904 with the Metropolitan Railway (MR) extension from Harrow to Uxbridge. This part of Middlesex was hitherto undeveloped, with only a single intermediate station at Ruislip at the time of opening. Rayners Lane is believed to have been used as an intermediate block post, a primitive technological precursor to signal boxes. The area's name referenced the adjacent country lane named after a local farmer. While the MR had always intended to open the Uxbridge branch with electrically powered rolling stock, steam traction had to be used for the first six months.

Rayners Lane Halt opened on 26 May 1906 and was typical of the rural halts built by the MR with exposed wooden platforms and basic shelters. On 1 March 1910, Rayners Lane Halt became a railway junction with the extension of the District Railway (DR) from South Harrow. A signal box (prefix P) had been established with a 30-lever frame.

London Transport

The MR and the DR, the latter of which was already part of Underground Electric Railways of London (UERL), were incorporated into the London Passenger Transport Board (LPTB) under the umbrella of London Transport (LT). With this merger came a raft of investment packages aiming to standardise the operational infrastructure of the underground network.

On 23 October 1933, the Piccadilly line replaced the District line service from South Harrow. In 1935, LT embarked on its New Works Programme. This substantial investment package culminated in the standardising of signalling standards and the mass rebuilding of stations, especially in suburbia, to cater for the proliferation of new housing developments in the home counties.

On 20 October 1935, the current signal cabin opened on a new site, retaining the same P prefix. It had an electrically interlocked Westinghouse N-style frame of 35 miniature levers. Unlike more conventionally designed frames, most of the levers on this frame were route levers, controlling a combination of signal and point slots instead of individual signals and points. The aim was to reduce the time required by the signaller to set up multiple routes in areas of high traffic density, such as a junction area like Rayners Lane. The exact layout was later adopted on a larger scale for the replacement Harrow-on-the-Hill signal cabin, which opened in 1948.

Rayners Lane station itself was rebuilt into its present form, opening on 8 August 1938 to an art deco design by Charles Holden and Reginald Uren. Like many of the art deco station rebuilds commissioned by LT, the simplistic brick and concrete construction found its way into operational buildings including depots, Interlocking Machine Rooms (IMR) and signal cabins.

Signal concentration

The incorporation of route lever working at Rayners Lane enabled the immediate concentration of adjacent signal cabins, starting immediately with Harrow Gas Works, which was subsequently controlled remotely from Rayners Lane via a relay room located on Roxeth Viaduct. This arrangement lasted until 1956 when goods traffic ceased, and the track layout was plain-lined. 1957 saw Rayners Lane absorb control of the South Harrow area, replacing the mechanical lever-framed DR signal cabin with a remotely operated IMR. This was followed by the Ruislip area on 27 September 1975, replacing an MR mechanical signal cabin with another IMR. Whilst the bulk of the control interface at Rayners Lane consisted of miniature levers, the added areas were controlled by push button panels reflecting the latest developments by Westinghouse in maximising the efficiency of equipment and signallers alike.

In 1978, Rayners Lane ceded control of South Harrow IMR to Earls Court control room, the first sizeable amphitheatre-style control room capable of monitoring signalling and service control of entire lines. This had been made possible by programme machines setting signals and points to a pre-loaded timetable with signallers only required to intervene during disruption via push button desks to interpose timetable commands.

Between 1985 and 1987, the original Westinghouse N-style miniature lever frame at Rayners Lane was replaced by an updated push button desk layout within the confines of the existing building and utilising the same structures that the levers sat within. This was to coincide with Rayners Lane absorbing control of the entirety of the Uxbridge Branch, with the only other remaining signal box on the branch at Uxbridge closing simultaneously. It was anticipated that this hybrid signal cabin would eventually be absorbed into the Baker Street control room along with the remaining signal cabins on the Metropolitan line at Harrow-on-the-Hill, Rickmansworth and Amersham.

Baker Street control room (opened 1986) was the third example on the Underground of the large control rooms. Earl's Court pioneered in the 1960s and rapidly became the preferred option to consolidate signalling. The extended geographic scope that controls rooms offered an obvious advantage, not to mention that many of the existing signal cabins were already considered reaching the end of their serviceable lives. However, a period of financial uncertainty within LT brought this signal concentration scheme to a premature end. Baker Street control room could only absorb control of the northwestern portion of the Circle line, the Metropolitan line south of Preston Road and the Jubilee line. As a result, the interim provision for the takeover of signal cabins, including Rayners Lane, continues unused to this day.

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 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 delayed five years' completion.

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 Rayners Lane lies in SMA 14 concerning the railway between West Harrow and Uxbridge. Whilst the signal cabin will close with the commissioning of SMA 14, colour light signals will initially remain in place on the Uxbridge branch to retain interoperability with 1973 stock trains used by the Piccadilly line, which given their impending replacement, have not received modifications to be ATO compatible.