Interlocking machine room


An Interlocking machine room 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.
Interlocking Machine Rooms are often fitted with fire suppression systems, generally based on carbon dioxide, to extinguish accidental fires and minimise damage to the equipment.
The table below is an alphabetical listing of the extant Interlocking Machine Rooms on the London Underground network in August 2019.
IMR CodeIMR name / locationLU LineLocationMultiple codes controlled
BBQueen's Park DepotBakerloo
BDPaddingtonBakerlooin middle of platform
BMBaker StreetBakerloo
BPPiccadilly CircusBakerloo
BR BSWaterlooBakerloo
ECEarl's CourtDistrictat end of platform
EDHigh Street KensingtonDistrict
EDTriangle Sidings District
EEGloucester RoadDistrict
EFSouth KensingtonDistrict
EGMansion HouseDistrict
EHEmbankmentDistrictat street level
EJTower HillDistrictin middle of platform
ENWhitechapelDistrictwithin manned cabin
FBBromley-by-BowDistrict
FCPlaistowDistrict
FEEast HamDistrict
FFBarkingDistrictwithin manned cabinFB – FG
FFBarking Sidings WestDistrict
FFBarking Sidings EastDistrict
FGDagenham EastDistrict
FJHornchurchDistrict
FMUpminsterDistrictwithin manned cabinFJ – FM
FMUpminster WestDistrict
JEustonNorthern
JBHarrow-on-the-Hill North SubsidiaryMetropolitan
JBHarrow-on-the-Hill South SubsidiaryMetropolitan
JEWillesden GreenMetropolitan Jubilee
JFNorthwoodMetropolitan Jubilee
JJWatford South JunctionMetropolitan
JM MMNeasden DepotJubilee
JPHarrow-on-the-HillMetropolitanwithin manned cabinJB subsidiaries and JF
JPWatfordMetropolitan
JPRickmansworthMetropolitanwithin manned cabinJP, JJ
JTChalfont & LatimerMetropolitan
JWAmershamMetropolitanwithin manned cabinJW, JT
LKing's CrossNortherninside former cabin
MBBaker StreetMetropolitanunder platforms 1 & 2
MDFinchley RoadMetropolitanwas MD JB
MG JGWembley ParkMetropolitan
MLSwiss CottageMetropolitan
MPRayners LaneMetropolitan Piccadilly
MURuislip SidingMetropolitan Piccadilly
MWUxbridge SidingsMetropolitan Piccadilly
OBAldgateDistrict Metropolitan
ODLiverpool StreetMetropolitaninside former cabin
OEMoogateMetropolitan
OHFarringdonMetropolitan
OJKing's Cross St PancrasMetropolitanat end of platform
PBGreen ParkPiccadillyat end of platform
PDHolbornPiccadilly
PGWood GreenPiccadillyat end of platform
PJArnos GrovePiccadilly
PKOakwoodPiccadillyinside former cabin
PMCockfostersPiccadillyinside former cabin
VKFinsbury ParkVictoria
WBWest Kensington EastDistrict Piccadillyinside former cabin
WCWest Kensington WestDistrict Piccadilly
WDHammersmithDistrict Piccadilly
WFParsons Green EastDistrict
WFParsons Green WestDistrict
WGPutney BridgeDistrict
WKWaterlooWaterloo and Cityinside former cabin
WKTurnham GreenDistrict Piccadilly
WLActon Town District
WLActon Town District
WMEaling CommonDistrict
WMHanger Lane junctionDistrict
WPEaling BroadwayDistrictinside former cabin
WRNorthfields DepotPiccadilly
WSBoston ManorPiccadilly
WTHounslow CentralPiccadilly
WVSouth HarrowPiccadilly
WWHatton CrossPiccadillyat end of platform
WYHeathrow Terminals 2 and 3Piccadillyat end of platform
WZHeathrow 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 2019.
IMR CodeIMR name / locationLU LineLocationMultiple codes controlledDecommissioned
ACColindaleNorthernat end of platform2008-19
AEEdgwareNortherninside former cabin2008-19
BKenningtonNorthern2008-19
BShoreditchEast London2002-08
CCharing CrossNortherninside former cabin2008-19
CGWhite CityCentralwithin manned cabinEAB, NOA1994-2002
ECamden Town Northern2008-19
ECamden Town Northern2008-19
EABEaling BroadwayCentral1994-2002
ETCanal Junction East Londonwithin manned cabin1994-2002
ETNew Cross GateEast London1994-2002
FHampsteadNortherninside former cabin2008-19
GGolders Green SouthNorthern2008-19
GGolders Green NorthNorthern2008-19
HONHolbornCentral1994-2002
JLStanmore SidingsJubilee2008-19
LBLiverpool StreetCentralin manned cabin in middle of platform1994-2002
LCBethnal GreenCentralin manned cabin in middle of platform1994-2002
LFLeytonstoneCentralin manned cabin1994-2002
LJWoodfordCentralin manned cabin1994-2002
LLHainaultCentralin manned cabinAlso controlled LL Grange Hill subsidiary area1994-2002
LPNewbury ParkCentralin manned cabin1994-2002
LTLoughtonCentralin manned cabin1994-2002
LUDebdenCentralin manned cabin1994-2002
LWEppingCentralin manned cabinLW, LX1994-2002
LXNorth WealdCentralin former manned cabin1994-2002
MMoorgateNortherninside former cabin2008-19
MAAMarble ArchCentral1994-2002
NNArchwayNortherninside former cabin2008-19
NOANorth ActonCentral1994-2002
NORNortholtCentralat end of platform1994-2002
NPEast FinchleyNortherninside former cabin2008-19
NQFinchley CentralNortherninside former cabin2008-19
NUHigh BarnetNortherninside former cabin2008-19
OPEdgware RoadMetropolitanwithin manned cabin2008-19
OZHammersmithMetropolitanwithin manned cabin2008-19
QUEQueenswayCentralat end of platform1994-2002
RUGRuislip GardensCentral1994-2002
TFGreen ParkJubilee2008-19
TGCharing CrossJubileeat end of platform2008-19
UStockwellNorthern2008-19
VEBrixtonVictoriaat end of platform2008-19
VFVictoriaVictoriaat end of platform2008-19
VGWarren StreetVictoriaat end of platform2008-19
VHKing's Cross St PancrasVictoriaat end of platform2008-19
VJHighbury & IslingtonVictoria2008-19
VLSeven SistersVictoria2008-19
VNNorthumberland Park DepotVictoria2008-19
VPWalthamstow CentralVictoriaat end of platform2008-19
WTooting BroadwayNorthernat end of platform2008-19
WERWest RuislipCentralwithin manned cabinWER, RUG, NOR1994-2002
XAngelNorthernin former manned cabin at end of platform1994-2002
YMordenNorthern2008-19