🔠 A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z
| ELR | Route | Section | Remarks |
|---|---|---|---|
| FAB | Farnley Mineral Branch | Understood to be disused | |
| FAL1 | Falmouth Branch | Penwithers Jn to COM (Pascoe deviation) | |
| FAL2 | Falmouth Branch | COM (Pascoe deviation) to COM (Penryn deviation) | |
| FAL3 | Falmouth Branch | COM (Penryn deviation) to Falmouth Docks | |
| FAS | Fletton Ash Loop | Fletton Ash Sidings | Understood to be disused |
| FBZ | Fochriw Colliery Branch | ||
| FCO | Ormskirk to Farington Curve Jn | ||
| FDM | Faversham Jn to Dover Marine Jn | ||
| FEC | Filton East Curve | Stoke Gifford No. 1 Jn to Filton No. 1 Jn | |
| FED | Felixstowe Beach Jn to Felixstowe Dock | ||
| FEL | Westfield Jn to Felixstowe Town | ||
| FEP | Leamside Branch | Tursdale Jn to Pelway Jn | Understood to be disused |
| FFH1 | Folkestone Harbour Branch | Folkestone East Jn to Limit of Headshunt for Harbour Branch | Understood to be part closed |
| FFH2 | Folkestone Harbour Branch | Folkestone East Yard Jn to Folkestone Harbour | Understood to be part closed |
| FGW | Forest Gate Jn to Woodgrange Park Jn | ||
| FHG | Forth Goods (Railway Street Sidings) | ||
| FHR1 | Farrington Curve Jn to Hall Royd Jn | Farrington Curve Jn to former Engine Shed Jn | |
| FHR2 | Farrington Curve Jn to Hall Royd Jn | former Engine Shed Jn to Lostock Hall Jn | |
| FHR3 | Farrington Curve Jn to Hall Royd Jn | Lostock Hall Jn to Bamber Bridge Jn | |
| FHR4 | Farrington Curve Jn to Hall Royd Jn | Bamber Bridge Jn to Blackburn Station West | |
| FHR5 | Farrington Curve Jn to Hall Royd Jn | Blackburn Station West to Gannow Jn | |
| FHR6 | Farrington Curve Jn to Hall Royd Jn | Gannow Jn to Hall Royd Jn | |
| FJH | Frodsham Branch | Halton Jn to Frodsham Jn | |
| FJJ | Cosham Spur | Cosham Jn to Farlington Jn | |
| FJL | Ford Jn to Littlehampton Jn | ||
| FJS1 | Waterloo Connection Line | Fawkham Jn to Southfleet Jn | |
| FKW | Ferrybridge North Jn to Knottingley West Jn | ||
| FLL1 | Longhedge ‘A’ Jn to Clapham Jn (western side) | Longhedge ‘A’ Jn to Factory Jn | |
| FLL2 | Longhedge ‘A’ Jn to Clapham Jn (western side) | Longhedge ‘A’ Jn to Lavender Hill Jn | |
| FLL3 | Longhedge ‘A’ Jn to Clapham Jn (western side) | Ludgate Line to Clapham Jn (western side) | |
| FLT | Folkestone Eurotunnel Terminal | Cheriton Jn to Terminal to Cheriton Jn | |
| FNS1 | Frome and North Somerset Line | Frome North Jn to former Frome West Jn | |
| FNS2 | Frome and North Somerset Line | former Frome West Jn to Radstock | |
| FOG | Forth Goods Sidings | ||
| FOM | Fletton Loop | Fletton Jn to Orton Mere | |
| FOR | Fords Branch | Fords Jn to Ford Factory (Bridgend) | |
| FOY | Fowey Branch | St Blazey to Fowey | |
| FRA | Frome Avoiding Line | Clink Road Jn to Blatchbridge Jn (via Frome Avoider) | |
| FRC1 | Frickley Colliery Branch | Moorthorpe to Frickley Colliery | Understood to be disused |
| FRY | Friary Branch | former Friary Jn to Plymouth Friary | |
| FSH | Fishguard Harbour Lines | NR boundary to Fishguard Harbour sidings | |
| FSS1 | London Fenchurch Street to Shoeburyness | Fenchurch Street to Barking West Jn | |
| FSS2 | London Fenchurch Street to Shoeburyness | Barking West Jn to Southend Central | |
| FSS3 | London Fenchurch Street to Shoeburyness | Southend Central to Shoeburyness | |
| FTB | Fareham West Jn to Bedenham Sidings (Brockhurst) | ||
| FTC | Channel Tunnel Rail Link (CTRL / HS1) | Folkestone Eurotunnel Terminal to Calais-Coquelles Eurotunnel Terminal | [mapping of route stops at mainland limit] |
| FTL | Farringdon Jn to Blackfriars | ||
| FUR | Furzebrook Branch | Worgret Jn to Furzebrook Sidings | |
| FWC | Filton West Curve | Filton No. 2 Jn to Filton West No. 2 Jn | |
| FWR1 | Rossington Colliery Branch | Headshunt to Rossington Colliery Jn | |
| FWR2 | Rossington Colliery Branch | Rossington Colliery Jn to Flyover West Jn |