Rickmansworth signal cabin

Rickmansworth
JP
Overview
Opened	6 December 1953
Operator	London Underground

Rickmansworth (prefix JP) is a signal cabin located within the station of the same name on London Undergrounds' Metropolitan line as part of the Sub-Surface Railway (SSR). It is scheduled for closure by 2023 under the Four Lines Modernisation (4LM) re-signalling programme.

Metropolitan Railway

The railway in this area opened on 1 September 1887 as the terminus of the Metropolitan Railway (MR) extension from Pinner. In 1889 Rickmansworth became a through station when the MR extended westwards to Chesham. Little is known about the first signal box at Rickmansworth other than records which show that it was replaced in 1889 with a new signal box (prefix K) equipped with 33 full size levers for the Chesham extension and a goods yard in the vicinity.

In 1898, the London Extension of the Great Central Railway (GCR), the last mainline to be built into London during the Victorian era, saw services between Harrow, Rickmansworth, Amersham, Chesham, and Aylesbury shared between the MR and GCR. Whilst the GCR and MR where commercial competitors in broad terms, they maintained a close working relationship with significant interworking across passenger and goods trains being commonplace. This was reflected in 1906 with creation the Metropolitan & Great Central Joint Railway (MGCJR) which aimed to put into law the shared operating agreements which had at times led to acrimonious disputes.

In 1923, the GCR was amalgamated through the Railways Act (1921) grouping it and other geographically linked railway companies into the London & Northern Eastern Railway (LNER). Along with the London Midland & Scottish Railway, Great Western Railway and Southern Railway, these railway companies formed the ‘Big Four’ whose size was thought by government was thought to be an insurance policy guaranteeing financial security in the years following the Great War. The MR which was fiercely protective of its independence was not included in these plans and even though the GCR had been dissolved, the name lived on through the MGCJR.

Electrification of MR services had been steadily progressing on its inner suburban services since 1905 and reached Rickmansworth in 1925 becoming the new locomotive changeover point between electric and steam traction. The shared running agreements via the MGCJR meant that it was not uncommon for LNER locomotives to haul MR passenger trains and MR locomotives on LNER goods trains. 1925 also saw the addition of a south facing bay platform at Rickmansworth for a shuttle service to Watford and the signal box was extended accordingly to accommodate this. Whilst shared running agreements to Watford for the LNER existed, they were not exercised, and the shuttle service would remain exclusively operated by the MR.  

London Transport

1933 saw the formation of the London Passenger Transport Board (LPTB) which finally integrated the MR with the other underground lines previously controlled by Underground Electric Railways of London. With this newly unified network came a desire to standardize its infrastructure and dispense with many of the operating quirks that the MR had vociferously used in the past to justify its independence. Whilst many of these ambitions where heavily delayed by the outbreak of WW2, 1953 saw the opening of the current signal cabin at Rickmansworth equipped with a Westinghouse N-style lever frame totalling 47 levers. The N-style minature lever frame represented the final development of mechanical lever frames by Westinghouse. Just a few years after Rickmansworth signal cabin was commissioned, the development of push button desks was already superseding lever frames as the preferred control method for signal cabins on the underground. Watford South Junction came under the control of Rickmansworth in 1955 through the addition of a push button panel above the existing lever frame. Watford station was added in 1958 and was controlled via programme machines which set routes and signals via a pre-loaded timetable.

Metropolitan line services to Aylesbury were withdrawn when electrification reached Amersham in 1960 doing away with the final steam hauled passenger services operated by London Transport. It also marked the steady decline of the former Great Central Mainline whose goods traffic had been in terminal decline since demobilisation after WW2 and passenger traffic was diverted onto other arterial routes. Whilst traffic levels would never reach the intensity or diversity seen before the 1960’s, the signal cabin has remained relatively untouched since then and continues in operation today with Chiltern Railways being the last remnants of the GCR service between London Marylebone and Aylesbury.

Four Lines Modernisation (4LM)

It was the introduction of the S8 and S7 stocks between 2010 and 2015 that was to prove 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 to be 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 with 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 which had been renamed as 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 Rickmansworth lies in SMA 13 concerning the railway between Moor Park, Watford, Amersham, and Chesham. Whilst the signal cabin itself will close with the commissioning of SMA 13 by 2023, colour light signals will remain in place to retain interoperability with Chiltern Railways trains which have not received modifications to be operable with CBTC.