Old Oaks Common TMD

Old Oak Common TMD is a Traction Maintenance Depot situated to the west of London, in Old Oak Common. The is the main facility for the storage and servicing of locomotives and multiple-units which utilise Paddington Station. The depot codes are 'OC' for the diesel depot, and 'OO' for the carriage shed. In steam days the shed code was 81A.

The area is also the location where two GWR main lines bifurcate: the 1838 route to Reading via Slough, and the 1906 New North Main Line via Greenford to Northolt Junction, the start of the Great Western and Great Central Joint Railway line. The former is in use for regular passenger services; the latter is used overwhelmingly by freight trains and ECS movements, though the 2007 timetable shows a single weekday train from Gerrards Cross via West Ruislip to Paddington.

GWR
Following the reconstruction of Paddington Station and the introduction of larger locomotives and new routes, the Great Western Railway required a larger depot than that at the 1855 constructed Westbourne Park, at which to service its locomotives and carriages.

In 1901, a site was acquired in South Acton, south of the Grand Union Canal and on the upside of the mainline. Taking four years to layout and build, designed by G.J. Churchward, it was the largest depot on the entire GWR system, and set the pattern for similar depots throughout the GWR including Tyseley.

It had four 65 ft undergirder turntables, under six-spans of east-west aligned northern-light pitched roofs. The shed covered a total area of 360 ft (six bays of 60 by} (six bays of 74 ft). The roofs were made of wood and steel rafters covered in Welsh slate tiles, supported on steel or cast iron columns, with solid London Brick Company walls. Laid out in an interconnecting 4-square pattern under the roof, each electrically operated turntable was fully boarded, and had 28 tracks spanning from it, able to accommodate locomotives up to 75 ft in length.

The associated repair shop, termed "The Factory", was allocated to the northeast front of the depot, with 11 roads approached over an electric traverser, and a 12th road direct from the depot throat. Built in a similar style to the depot, it was 195 ft by 110 ft in size, and housed a  30 LT crane. There were also separate Smithy and carpenters shops, a stores and a general office.

The approach to the shed housed a standard GWR pattern coal stage, again the largest on the system. It was approached via a 1:50 gradient brick-arch supported ramp, with 1:80 beyond the stage. In 1938, the approach roads to and from the coal stage were doubled, and in 1942 an ash shelter constructed to protect from Nazi Luftwaffe bombing. The four water tanks housed over the stage held 290000 impgal of water, while sand was supplied from a separate sand furnace.

The whole depot came into operation from 17 March 1906, and became the head of the GWR London operating division.

British Railways
Throughout its GWR and early BR operational life, the depot remained fairly intact and similar to its original layout. The only major difference by the early 1960s was the addition of a pre-war diesel refuelling stage just north of the repair shop, for use by GWR railcars.

With a reduction in steam traction and the implementation of the Beeching axe, in March 1964 the decision was taken to move the remaining steam locomotive allocation to the 1950s designed Southall MPD, and reconstruct Old Oak Common as a diesel depot. Within a year the majority of the GWR 1906 depot was demolished, with only "The Factory" repair shop, furthest western turntable and parts of the stores remaining.

Just south of the residual GWR buildings, in the 1960s BR built what was initially the storage depot for the Blue Pullman trains, what later became known as the Coronation Carriage Sidings. In the late 1970s, south of this and almost adjacent to the Great Western Main Line, they built an InterCity 125 depot. Today trains which operate the First Great Western services are maintained here.

In 1997 a new bespoke depot was constructed at the southern end of the site, between the Great Western depot and the main line, funded by the British Airports Authority (BAA) to service and maintain the Heathrow Express (HEX) and Heathrow Connect service trains. This was the first new privately funded train depot in the UK since the British railways nationalsation in 1948. The inauguration of the HEX services saw the electrification of the GW main line from Paddington to Hayes and onto Heathrow airport using 25kV overhead catenary.

The residual GWR buildings were used from the 1970s to house and maintain singular diesel locomotives, special trains, and maintain carriages and freight stock in the area. On the privatisation of BR, the buildings were allocated to English Welsh and Scottish Railway, and latterly operated by their commercial subsidiary Axiom Rail. In 2009, this site, together with the adjacent Coronation Carriage Sidings was fenced off due to compulsory purchase for the Crossrail project. All the remaining GWR buildings and the Coronation Carriage Sidings were demolished by mid-2011, with the former western shed turntable donated to the Swanage Railway.

Present
Developments in recent years have been on the southern section of the former GWR site, either side of the 1970s BR High Speed Train depot. This has been added to in width, and now services trains operated by First Great Western, Heathrow Express and Heathrow Connect. The allocation is presently:


 * Class 43 High Speed Train – used for First Great Western long-distance express services
 * Class 180 – five 'Adelante' diesel multiple unit used for semi-fast services – and also to assist Hull Trains with maintenance of their four 180s.
 * Class 57 – locomotive used for First Great Western Night Riviera Sleeper services
 * Class 165 – two- or three-coach Turbo DMU used on commuter services to London (ex First Great Western Link)
 * Class 166 – three-coach Turbo DMU used on longer commuter services to London (ex First Great Western Link)
 * Class 360 – five-coach EMU used on Heathrow Connect services (joint operation with BAA)
 * Class 332 – four- and five-coach EMU used on Heathrow Express services.

Detailed design work is now underway in preparation for the construction of another new depot, this time on the northern part of the site. This will effectively replace the former locomotive depot and the Coronation Sidings area. It will provide full servicing, maintenance and storage for the proposed new fleet of Crossrail trains which will operate between Maidenhead on the Great Western main line and Shenfield on the Great Eastern main line, using a newly constructed tunnel running West-to-East under London. The new development is large and will effectively fill up the remaining area at Old Oak Common.

At the time of writing Old Oak Common is also being considered as the location for a major interchange station between the GW main line, Crossrail, Heathrow Express and the proposed HS2 high speed line from London (Euston) to Birmingham/Manchester/Leeds.

North Pole depot
South of the line is North Pole depot, also approximately half a mile south-west of Willesden TMD. Here until 2010, Eurostar trains which operate the Channel Tunnel had their UK maintenance base. With the opening of the new international terminal at St Pancras railway station, all servicing was moved to the new Temple Mills depot located near Stratford International.

Writing in 2012, this depot site is now being considered for conversion to provide for the maintenance and repair of the proposed new Intercity Express Programme (IEP) trains which are expected to replace High Speed Train sets on the Great Western main line from 2016.