Hammersmith signal cabin
| Hammersmith | |
|---|---|
| OZ | |
| Overview | |
| Opened | 24 June 1951 |
| Closed | 16 March 2019 |
| Operator | London Underground |
Hammersmith (prefix OZ) was a signal cabin located near the station of the same name on the Circle and Hammersmith & City lines of London Underground’s Sub-Surface Railway (SSR). It was the first of the signal cabins to be closed under the Four Lines Modernisation (4LM) re-signalling programme in March 2019.
Metropolitan Railway[edit | edit source]
The railway in this area opened on 13 June 1864 with the Metropolitan Railway (MR) extension from Paddington to Hammersmith. In common with the first section of the MR between Paddington and Farringdon, this was a joint undertaking between the MR who used standard gauge and the Great Western Railway (GWR) which at this time used 7ft broad gauge. As a result, the railway from Farringdon to Hammersmith was built to dual gauge standards.[1] The use of broad gauge only lasted until 1892, and the additional wider rail was removed leaving behind some of the most generous gauge clearances on the Underground. Little is known about the original signal box that opened with the line or the signal box that replaced it in 1884.
In 1908, a new signal box (prefix H) was opened. Built to GWR standards and equipped with a 63-lever frame, it was situated close to the short lived Hammersmith (Grove Road) station which itself was controlled from a separate signal box. At this time, the MR was handling substantial volumes of goods traffic from the GWR in addition to the three-track terminal station and the carriage depot adjacent to the box.
London Transport[edit | edit source]
The most current signal cabin at Hammersmith (prefix OZ) opened on 24 June 1951 and was equipped with a Westinghouse ‘N style’ electrically interlocked frame of 35 ‘full stroke’ miniature levers. Despite the proliferation of goods yards, between Paddington, Latimer Road and Hammersmith still very much active in the 1950’s, Hammersmith (Met) remained something of a back water. As a result, it was not a key focus of the signal concentration schemes from the 1960’s onwards that gave London Underground the pioneering amphitheatre style control rooms overseeing the signalling and service control of entire lines.
The introduction of the C69 Stock in 1970 had raised hopes of re-signalling the Circle line utilising much of the pioneering Automatic Train Operation (ATO) technology used on the Victoria line which had opened in stages a year earlier.[2] However, financial difficulties within London Transport coupled with a downturn in passenger numbers that would come to dominate the underground into the 1980’s meant that this scheme along with many others was shelved in favour of piecemeal upgrades. As a result, the passive provision for ATO on the C stock would remain completely unutilised for the rest of their operational lives.
Four Lines Modernisation (4LM)[edit | edit source]
In 2007, it was announced that the Sub-Surface Railway (SSR) would receive a unified fleet of 192 trains of S7 and S8 Stock built by Bombardier Transportation at Derby replacing the A60, A62, C69, C77 and D78 Stocks. Following on from this, the SSR would also be subject to wholesale re-signalling called the Sub-Surface Upgrade Programme (SSUG) the contract of which was won by Bombardier using their Distance-To-Go-Radio (DTGR) moving block signalling system in 2011.
With the roll out of the S Stock well underway, by 2013 it was becoming apparent that Bombardier’s relative inexperience in delivering signalling systems was starting to drag SSUG behind schedule and London Underground subsequently terminated the contract that year at an estimated cost of £900m and a forecasted delay to the final completion date of the project of at least 5 years.
The retendered contract for SSR re-signalling was won by Thales in 2015 utilising Communications Based Train Control (CBTC), a variant of SelTrac. By now the project had been renamed as the Four Lines Modernisation (4LM). Transition from legacy fix-blocked signalling to CBTC across the SSR was split into 15 Signal Migration Areas (SMA) starting with SMA 0.5 between Hammersmith (Circle and Hammersmith & City lines) and Latimer Road. Following intensive testing and a series of aborted go-live dates, Hammersmith signal cabin was switched out for the final time after traffic in the early hours of 16 March 2019. SMA 0.5 was subsequently pressed into revenue earning service on afternoon of 17 March 2019 controlled from Hammersmith Service Control Centre (SCC).