From the introduction of TOPS in 1973, all British Rail diesel and electric locomotives and multiple units were allocated to a particular traction maintenance depot or TMD. Drawing from the terminology of steam traction, these depots were generally referred to as "sheds", and indeed most locations were those which had possessed depots for steam locos. Each TMD had a two-character code which was originally displayed underneath the number of each locomotive allocated there. Later this was extended to cover each carriage of diesel multiple units (DMUs), and even some coaching stock; at this time additional depot codes were added covering places with coaching stock allocations, and also works locations.
Allocations and TOPS depot codes
Locations given a TOPS code included all TMDs, servicing depots (where minor work such as A exams could be undertaken), and some stabling points (SPs) where locomotives or multiple units would be parked when not required. The locations varied from comprehensively equipped depots, through covered accommodation with fuelling point, to a mere siding. The use of TOPS codes for SPs was somewhat haphazard, with Machynlleth (code MN) hosting one or two locomotives on some weekends while Wolverhampton station, which had no TOPS code, stabled more than a dozen locos.
The application of a depot code was generally reliable as a guide to the base from which the locomotive or multiple unit operated but with some variations, mainly relating to shunters and departmental locomotives.
EMU depots such as Birkenhead North (BD) often required a diesel shunter for moving stock when not powered. As there was no fuelling or maintenance capability at BD, a shunter allocated to nearby Birkenhead Mollington Street (BC) was used, returning to its home depot every four weeks. This arrangement also existed at other locations such as Ilford/Stratford.
Departmental locomotives, by the nature of their use, were sometimes reported as allocated to a base location or even to a region in general rather than an official depot. The Western Region sometimes followed this practice, with number 20 (latterly 97020) reported as allocated to "Reading Signal Works" throughout the 1970s. Locomotives used for research purposes would be reported as allocated to the Derby Research Centre.
List of TMD, Servicing Depot, SP and other non-works codes
+ TOPS code Shed name Origins CommentsAB Aberdeen Ferryhill AC Aberdeen Clayhills Carriage maintenance depotAF Ashford Chart Leacon AK Manchester ArdwickAL Aylesbury AN Allerton AY Ayr BA Basford Hall (Crewe) BB Beachbrook Farm EWS BC Birkenhead Mollington Street LNWR and GWR jointBC Bicester BC Beachbrook Farm Freightliner BD Birkenhead North Wirral Railway EMU depot, from BN from 1976BE Bedford Midland Station No allocation - Fuelling Point only.BG Botanic Gardens (Hull) BG Billingham BH Barrow Hill (Staveley) Midland RailwayBI Brighton Lovers Walk EMU depotBJ Bristol Marsh Junction DMU depotBK Birkenhead Central Mersey Railway EMU depotBK Bristol Barton Hill from 1992BL Blyth BL Basford Hall Freightliner BM Bournemouth EMU depotBN Birkenhead North to BD from 1976BN Bounds Green HST depot, from 1976BP Beattock to 1976BP Blackpool Carriage maintenance depotBQ Bury EMU depot, from BV from 1975BR Bristol Bath Road GWRBS Bescot BT Bo'ness BU Burton BV Bury to BQ from 1975BW Barrow BW Barry BX Buxton DMU depotBY Bletchley BZ St. Blazey (Par) Cornwall Minerals RailwayCA Cambridge DMU depotCB Crewe Basford Hall CC Clacton EMU depotCD Crewe Diesel Depot CE Crewe Electric Depot CF Cardiff Canton CG Croxley Green EMU depot, to closure in 1985CG Crewe Gresty Lane GWRCH Chester CJ Clapham Junction No allocation.CK Corkerhill DMU depotCL Carlisle Upperby Carriage maintenance depotCM Camden Carriage maintenance depotCO Coquelles (France) CP Crewe Carriage Shed No allocation - Fuelling Point only.CQ Crewe Heritage Centre Crewe Heritage Centre Storage Facility & Heritage CentreCR Colchester CS Carnforth West Coast RailwaysCV Coalville CW Cricklewood CZ Central Rivers DA Darnall DMU depotDE Dewsbury DE Dundee DF Derby Fragonset DI Didcot Railway Centre DL Dollands Moor No allocation.DM Dagenham DM Dee Marsh DN Darlington DR Doncaster DT Dunfermline Townhill DY Derby Etches Park DMU depotEC Edinburgh Craigentinny HST depot Carriage Maintenance DepotED Eastfield EG Edge Hill EH Eastleigh EJ Ebbw Junction (Newport) EM East Ham EMU depotEN Euston Downside Carriage maintenance depotEU Euston Station EX Exeter St Davids FB Ferrybridge FF Brussels Forest (Belgium) Eurostar depotFH Frodingham (Scunthorpe) FP Finsbury Park FR Fratton (Portsmouth) EMU depotFW Fort William FX Felixstowe GC Cowlairs (Glasgow) Carriage maintenance depotGD Gateshead GF South Gosforth DMU depotGI Gillingham EMU depotGL Gloucester GM Grangemouth GU Guide Bridge GW Glasgow Shields Road Electric locomotive/EMU depotGY Garston Yard HA Haymarket HD Holyhead HE Hornsey EMU depotHF Hereford HG Hither Green HI Hitchin HM Healey Mills (Wakefield) HN Hamilton DMU depotHO Holbeck (Leeds) HQ BRB Headquarters Paper allocationHR Hall Road (Liverpool) EMU depotHS Hammerton Street (Bradford) HT Heaton HST and DMU depotHY Hyndland EMU depotIL Ilford EMU depotIM Immingham IP Ipswich Station No allocation - Fuelling Point only.IS Inverness KD Carlisle Kingmoor KK Kirkdale (Liverpool) EMU depotKM Carlisle Yard No allocation - Fuelling Point only.KN MoD Kineton KT MoD Kineton KX Kings Cross No allocation - Fuelling Point only.KY Knottingley LA Laira (Plymouth) Intercity HST, DMULC Longsight International Eurostar depotLE Landore (Swansea) LG Longsight Electric Depot (Manchester) Electric locomotive and EMU depotLJ Llandudno Junction LL Liverpool Edge Hill Carriage maintenance depotLM Long Marston (MoD) LN Lincoln DMU depotLO Longsight Diesel Depot (Manchester) LP Le Landy (Paris) Eurostar depot, to 1994LR Leicester LV Liverpool Street No allocationLY Le Landy (Paris) Eurostar depot, from 1994MA Manchester Longsight Carriage Maintenance Depot MB Middlesbrough MD Merehead ME Marylebone DMU depotMG Margam (Port Talbot) MH Millerhill (Edinburgh) ML Motherwell MN Machynlleth MR March MV Manchester Victoria (Red Bank) Carriage maintenance depotNA Newton Abbot South Devon RailwayNC Norwich Crown Point Carriage maintenance depotNG New Cross Gate Carriage maintenance depotNH Newton Heath (Manchester) Lancashire & Yorkshire Railway DMU depotNL Neville Hill (Leeds) HST and DMU depotNT Nottingham Carriage Sidings NM Northam NN Northampton NP North Pole International NR NorwichNW Northwich No allocation - Fuelling Point only.OC Old Oak Common OD Old Dalby OH Old Oak Common (Heathrow Express) Heathrow Express EMU depotOM Old Oak Common Carriage Maintenance Depot ON Orpington EMU depotOO Old Oak Common (HST) HST depotOX Oxford OY Oxley (Wolverhampton) Carriage maintenance depotPA St Pancras No allocation.PB Peterborough PC Polmadie Carriage Maintenance Depot (Glasgow) PH Perth Station PI North Pole International 1994-1995PM Bristol St Phillips Marsh HST depotPO Polmadie (Glasgow) PQ Parkeston Quay PZ Penzance RB Ranelagh Bridge No allocation - Fuelling Point only.RE Ramsgate EMU depot. Changed to RM.RG Reading DMU depotRL Ripple Lane RM Ramsgate EMU depot. Was RE.RR Radyr RS Reddish RU Rugby RY Ryde EMU depotSA Salisbury SB Shirebrook SD Selafield Direct Rail ServicesSE St Leonards DEMU depotSF Stratford SG Slade Green EMU DepotSI Soho (Birmingham) SL Stewarts Lane Electric locomotive and EMU depotSN Stranraer SP Wigan Springs Branch SQ Stockport SR Stratford Repair Depot ST Severn Tunnel Junction SU Selhurst EMU depotSV Wembley Chiltern SW Swindon SY Saltley (Birmingham) SZ Southall DMU depotSZ Southampton Maritime FreightlinerTB Three BridgesTD Temple Mills TE Thornaby (Tees) TF Thornton Fields (Stratford) Carriage maintenance depotTG Tonbridge TI Tinsley (Sheffield) TJ Thornton Junction TL Tilbury TN Taunton TO Toton TP Trafford Park TS Tyseley DMU depotTW Tunbridge Wells West Station DEMU depotTY Tyne Yard VR Vale of Rheidol Railway (Aberystwyth) Steam locomotive depotWA Warrington Arpley WB Willesden Brent Sidings Carriage maintenance depotWC Waterloo & City line WD Wimbledon EMU depotWH Wath WH Whatley from 1994WJ Watford Junction No allocation - Fuelling Point only.WK Workington WN Willesden WO Wellingborough No allocation - Fuelling Point only.WS Worcester WT Westhouses No allocation - Fuelling Point only.WY Westbury YC York Clifton YK York
Works codes
+ TOPS code Works name Origins CommentsZB Doncaster Works Wabtec ZC Crewe Works ZD Derby Litchurch Lane Works ZE Derby Locomotive Works ZF Doncaster Works Bombardier transportation ZG Eastleigh Works ZH Glasgow Springburn Works ZH Glasgow St Rollox Works ZI Ilford works Bombardier transportation.ZL Swindon Works ZN Wolverton Works ZP Horbury (Wakefield) Bombardier transportation.
References
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