An Interlocking machine room (IMR) is a component of the London Underground signalling system. Interlocking is an arrangement of signal apparatus that prevents conflicting movements through an arrangement of tracks such as junctions or crossings. On the London Underground signals and points are operated and controlled by an array of electrical, pneumatic and mechanical components. IMRs are unmanned and generally located adjacent to points or at platform ends, and provide a secure and weatherproof enclosure for pneumatically controlled mechanically and electrically interlocked levers mounted horizontally in an upright lever-frame or with a converted manual lever frame.
The table below is an alphabetical listing of the extant Interlocking Machine Rooms on the London Underground network in August 2024. +London Underground operational Interlocking machine roomsIMR CodeIMR name / locationLU LineLocationMultiple codes controlledBBQueen's Park DepotBakerlooBDPaddingtonBakerlooin middle of platformBMBaker StreetBakerlooBPPiccadilly CircusBakerlooBR BSWaterlooBakerlooJBHarrow-on-the-Hill North SubsidiaryMetropolitanJBHarrow-on-the-Hill South SubsidiaryMetropolitanJFNorthwoodMetropolitanJJWatford South JunctionMetropolitanLKing's CrossPiccadillyMMNeasden DepotMetropolitan JubileeJBHarrow-on-the-HillMetropolitanwithin manned cabinJB subsidiaries and JFJPWatfordMetropolitanJPRickmansworthMetropolitanwithin manned cabinJP, JJJTChalfont & LatimerMetropolitanJWAmershamMetropolitanwithin manned cabinJW, JTMDFinchley RoadMetropolitanwas MD JBMG JGWembley ParkMetropolitanMPRayners LaneMetropolitan PiccadillyWith manned CabinMU, MWMURuislip SidingMetropolitan PiccadillyMWUxbridge SidingsMetropolitan PiccadillyPBGreen ParkPiccadillyat end of platformPDHolbornPiccadillyPGWood GreenPiccadillyat end of platformPJArnos GrovePiccadillyPKOakwoodPiccadillyinside former cabinPMCockfostersPiccadillyinside former cabinWDHammersmithDistrict PiccadillyWFParsons Green EastDistrictWFParsons Green West DistrictWGPutney BridgeDistrictWKWaterlooWaterloo and Cityinside former cabinWKTurnham GreenDistrict PiccadillyWLActon Town (East) DistrictWLActon Town (West) DistrictWMEaling CommonDistrictWMHanger Lane junctionDistrictWPEaling BroadwayDistrictinside former cabinWRNorthfields DepotPiccadillyWSBoston ManorPiccadillyWTHounslow CentralPiccadillyWVSouth HarrowPiccadillyWWHatton CrossPiccadillyat end of platformWYHeathrow Terminals 2 and 3Piccadillyat end of platformWZHeathrow Terminal 5Piccadilly As London Underground train control is modernised and updated some Interlocking Machine Rooms are made redundant. The table below is an alphabetical listing of the IMRs on the London Underground network that were operational in 1994 but had been decommissioned by August 2024. +London Underground decommissioned Interlocking machine roomsIMR CodeIMR name / locationLU LineLocationMultiple codes controlledDecommissionedACColindaleNorthernat end of platform2008-19AEEdgwareNortherninside former cabin2008-19BKenningtonNorthern2008-19BShoreditchEast London2002-08CCharing CrossNortherninside former cabin2008-19CGWhite CityCentralwithin manned cabinEAB, NOA1994-2002ECamden Town (Platform 1)Northern2008-19ECamden Town (Platform 4)Northern2008-19EABEaling BroadwayCentral1994-2002ETCanal Junction (south of Surrey Quays)East Londonwithin manned cabin1994-2002ETNew Cross GateEast London1994-2002FHampsteadNortherninside former cabin2008-19FBBromley-by-BowDistrictFCPlaistowDistrictFEEast HamDistrictFFBarkingDistrictwithin manned cabinFB – FGFFBarking Sidings WestDistrictFFBarking Sidings EastDistrictFGDagenham EastDistrictFJHornchurchDistrictFMUpminsterDistrictwithin manned cabinFJ – FMFMUpminster WestDistrictGGolders Green SouthNorthern2008-19GGolders Green NorthNorthern2008-19HONHolbornCentral1994-2002JEWillesden GreenMetropolitan JubileeJLStanmore SidingsJubilee2008-19JPRickmansworthMetropolitanwithin manned cabinJP, JJLBLiverpool StreetCentralin manned cabin in middle of platform1994-2002LCBethnal GreenCentralin manned cabin in middle of platform1994-2002LFLeytonstoneCentralin manned cabin1994-2002LJWoodfordCentralin manned cabin1994-2002LLHainaultCentralin manned cabinAlso controlled LL Grange Hill subsidiary area1994-2002LPNewbury ParkCentralin manned cabin1994-2002LTLoughtonCentralin manned cabin1994-2002LUDebdenCentralin manned cabin1994-2002LWEppingCentralin manned cabinLW, LX1994-2002LXNorth WealdCentral in former manned cabin1994-2002MMoorgateNortherninside former cabin2008-19MAAMarble ArchCentral1994-2002NNArchwayNortherninside former cabin2008-19NOANorth ActonCentral1994-2002NORNortholtCentralat end of platform1994-2002NPEast FinchleyNortherninside former cabin2008-19NQFinchley CentralNortherninside former cabin2008-19NUHigh BarnetNortherninside former cabin2008-19OPEdgware RoadMetropolitanwithin manned cabin2008-19OZHammersmithMetropolitanwithin manned cabin2008-19QUEQueenswayCentralat end of platform1994-2002RUGRuislip GardensCentral1994-2002TFGreen ParkJubilee2008-19TGCharing CrossJubileeat end of platform2008-19UStockwellNorthern2008-19VEBrixtonVictoriaat end of platform2008-19VFVictoriaVictoriaat end of platform2008-19VGWarren StreetVictoriaat end of platform2008-19VHKing's Cross St PancrasVictoriaat end of platform2008-19VJHighbury & IslingtonVictoria2008-19VKFinsbury ParkVictoriaVLSeven SistersVictoria2008-19VNNorthumberland Park DepotVictoria2008-19VPWalthamstow CentralVictoriaat end of platform2008-19WTooting BroadwayNorthernat end of platform2008-19WERWest RuislipCentralwithin manned cabinWER, RUG, NOR1994-2002WBWest Kensington EastDistrict Piccadillyinside former cabinWCWest Kensington WestDistrict PiccadillyXAngelNorthernin former manned cabin at end of platform1994-2002YMordenNorthern2008-19ENWhitechapelDistrictwithin manned cabin2021ECEarl's CourtDistrictat end of platform2022EDHigh Street KensingtonDistrict2022EDTriangle Sidings (Kensington)District2022EEGloucester RoadDistrict2022EFSouth KensingtonDistrict2022EGMansion HouseDistrict2021EHEmbankmentDistrictat street level2021EJTower HillDistrictin middle of platform2021MBBaker StreetMetropolitanunder platforms 1 & 22019MLSwiss CottageMetropolitan2019OBAldgateDistrict Metropolitan2021ODLiverpool StreetMetropolitaninside former cabin2021OEMoogateMetropolitan2021OHFarringdonMetropolitan2021OJKing's Cross St PancrasMetropolitanat end of platform2021LKing's CrossNortherninside former cabinJEustonNorthern
See also
Interlocking Liverpool Street signal box
References