31.10.13
Neasden depot upgrade
Source: Rail Technology Magazine Oct/Nov 2013
The major upgrade at Neasden depot to make it suitable for the routine maintenance of the S Stock trains on the Metropolitan line is now complete. Adam Hewitt reports.
Neasden is one of London Underground’s most complex depots, and needed a major overhaul to make it suitable for the new S Stock trains.
The upgrade itself, phase one of which began in 2010 and was completed this year, had to take place while maintenance of the Metropolitan line fleet continued, and while 20 Jubilee line trains were stabled there. The depot, situated between Neasden and Wembley Park stations, had never had a major refurbishment since it was rebuilt back in the 1930s.
The works included new maintenance facilities, and a new train lifting machine – one of the few in the UK – plus a training school, wheel lathe and cleaning shed.
Under the SSR upgrade programme, Neasden Depot will now provide light maintenance facilities for the Metropolitan line fleet and heavy maintenance for the whole Bombardier-built S Stock fleet of 191 trains.
The upgrade was split into two phases: phase A (worth £180m) was for the short to medium term (routine) maintenance operations, while phase B, currently at the concept design stage, would cover the heavy maintenance facilities (£60m).
Phase A was delivered via three main contracts – civils and M&E works were done by BAM Nuttall, signalling by Thales, and DC traction power works by Balfour Beatty Scott Wilson.
Civils and M&E
Work under the civils and M&E contract included two train lifting roads being provided within the new lifting shop (one in floor lifting system and the other floor mounted), plus an intercar gangway exchange road.
The contract saw an extensive E&M refit of the existing sheds and new E&M services for new sheds (including two new LVAC Switch Rooms) plus increased LVAC capacity with a new 1500kVA transformer room and upgrade of an existing transformer room from 800kVA to 1500kVA. It also included the renewal and reconfiguration of LVAC mains sub-distribution, which supports the operational buildings in the south end of the depot.
There was a bespoke ‘clean room’ for circuit board rectification built, and the contractor also delivered modular CMS in new sheds for electrical and mechanical services, which was prefabricated before installation and so significantly reduced installation time.
The contractor worked on the Garrandale motorised bogey turntables, a Heating Ventilation Air Conditioning (HVAC) Exchange road, and a new gas intake operating at medium pressure to support substantial increase in load with the new sheds, and wash function in the existing sheds.
The upgrade saw the rationalisation of storage at the depot, a modification of the train wash for the new S Stock trains, and an upgrade of the stabling and permanent way to suit the new build status and the signalling upgrade works.
Also included in this contract’s scope were the general purpose pitted maintenance roads, the door maintenance road, three ‘swimming pool’ exam/inspection roads, the cleaning roads and winterisation/sanding roads.
There was also a modification to the single wheel lathe road facility for the S Stock.
The civils contract also included the provision of the fleet training school, and an upgrade to the track north of Short shed.
Signalling
There are 137 signals within Neasden depot, and Thales’ role on the upgrade included the re-signalling of the depot with the installation and commissioning of Computer Based Interlocking (the first of its type in the UK) and associated trackside equipment, including axle counters for train detection.
The complicated technical interfaces between differing signalling technologies on the adjacent main lines (Jubilee and Metropolitan) and within the depot environment required complex systems integration management, LU said.
Thales installed and commissioned a new points system, the In-Bearer Clamp Lock, which was new to the LU infrastructure, as well as a new Signalling Equipment Room.
The pre-existing train movement room, which is operational 24/7, was refurbished and a secondary signalling control panel for use in the transition stage between the old and new systems was installed.
DC traction power
Balfour Beatty Scott Wilson upgraded the depot’s traction supplies to support the S Stock standing load, requiring the modification and upgrading of the DC supplies throughout the depot. It is now supplied by a new 10MW traction substation – the contractor had to create new DC sections for the stabling areas to support the load increase.
It built two new DC switch rooms to support the new shore supply systems in the shed areas, and new shore supplies with switched contactor arrangements have been installed to support S Stock loading.
Fault make load-break rated traction isolation switches have been fitted throughout the depot, and there was extensive new traction cabling and cable routes with control from the new substation being provided by Enterprise to all of these new sections.
The contractor also had to modify and upgrade the existing earthing arrangements for the entire depot.
The re-signalling had to be done with minimal disturbance to the live 24/7 depot environment and whilst continuing to provide maximal operational flexibility and functionality, before the decommissioning and removal of the existing signalling assets could be achieved.
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