Signal box prefix codes

A (hopefully) comprehensive listing

'Boxes beginning O

Last update 12 March 2022

Additional information is always gratefully received, whether entirely new records (particularly historical records) or information to fill in gaps or correct errors, via the contact link under the Miscellaneous entry in the navigation bar above. Thank you.

Please select a starting letter from the links below:

Code Signal Box Note ELR Mileage Opened Closed Control to
OA&GB Junction MVL1 6m 07ch 1965 14 January 1996 Ashton Moss North Junction (AMN)
O Oakenshaw Formerly named Oakenshaw North TJC3 182m 35ch 1928 23 December 2007last train; official closure 27 December 2007 Wakefield Kirkgate [new] (WK)
OK Unclear if code carried
ON Code used when named Oakenshaw North
R Repeater signals
UM Up line automatic signals
Oakenshaw North See Oakenshaw
OA Oakham Name board states 'Oakham Level Crossing' GSM2 93m 56ch 8 October 1899
O Unclear whether code used
Oakham Level Crossing See Oakham
OP Oakleigh Park ECM1 ≈8m 25ch 13 July 1924 30 May 1970 New Barnet (NB)
OT Oak Tree DSN1 ≈4m 28ch 7 October 1972 Darlington (D)
WO Oatlands BML1 18m 13ch 1894 22 March 1970 Surbiton [new] (S)
Oddingley Gate box: line controlled by Gloucester (G) BAG2 62m 61ch 1908
OF Offord & Buckden Downgraded to gate box 25 July 1976: line controlled by St Neots (SN) ECM1 55m 76ch 6 February 1899 17 May 1998 Peterborough (P)
OY Oldbury Downgraded to shunt frame 8 January 1966: line controlled by Birmingham New Street (NS) RBS2 5m 14ch ≈28 October 1981 Birmingham New Street (NS)
Old Dalby NNR GSM4 111m 22ch ?
OM Oldham Mumps MPR3 7m 21ch 1967 3 October 2009 Line transferred to Manchester Metrolink
F Old Kew Junction HOU 10m 04ch 18 October 1942 8 September 1974 Feltham (F)
LG Old Lea Station Temporary box intended for occasional use to increase capacity during Nottingham resignalling. Opened and immediately switched out, never used to signal trains. Lincoln to Gainsborough line signals SPD3 95m 68ch 30 June 2013 4 January 2014 Lincoln Control Centre (LG)
OO Old Oak Common MLN1 2m 64ch 8 October 1962 4 September 1967 Old Oak Common [new panel] (OO)
EC Engine and carriage line signals
OO Old Oak Common [new panel] MLN1 2m 64ch 4 September 1967 30 May 1995 Slough New IECC (SN)
DG Down goods and carriage line signals. Code used by 1974
DM Down main line automatic signals
DR Down relief line automatic signals
EC Engine and carriage line signals. Code used by 1971
OOO Code shown in 1984 notice in error
UC Up carriage line automatic signals
UM Up main line automatic signals
UR Up relief line automatic signals
UW Up Wycombe line automatic signals
Z Draw ahead signals at Hayes. Code used from 10 August 1983
C Old Oak Common Carriage Line Ground Frame Believed code not carried MLN1 ≈2m 00ch
CR Old Oak Common Crossrail Depot Codes shown on development plans MLN1
WL Old Oak Common Depot Wheel lathe line signals OOC1 28 December 2017
A Road A signals
B Road B signals
C Road C signals
OT Old Town DSN2 26 November 1967 Middlesbrough (M)
OM Olive Mount Junction DSE 2m 50ch 1883 18 May 1998 Edge Hill (LE)
OC Ollerton Colliery Burnt down April 2006 HIM 19m 33ch 1893 23 March 2009 Thoresby Colliery Junction (T)
OY Onibury SHL 22m 68ch 12 December 1977 Wales Rail Operating Centre (NS) (planned)
OL Ordsall Lane No 1 Believed code not carried COL ≈190m 20ch 18 October 1978 Deal Street (DS)
OC Orgreaves Colliery Ambiguous source data: colliery branch removed 8 February 1981 MAC3 45m 10ch 1901 8 September 1985 Darnall West Junction (DW)
OW Orient Way Sidings Code used from opening SDC ≈5m 70ch 2009
JE Orpington [panel] Code used from opening XTD 13m 49ch 4 March 1962 22 February 1993 Ashford IECC (AD)
JE Orpington A Code used from 1959 XTD 13m 47ch ≈1904 4 March 1962 Orpington [panel] (JE)
EBV Otford Junction Code used from 11 March 1962 SBJ 24m 55ch 1 January 1898 5 June 1983 Victoria Signalling Centre (VS)
A Automatic signals
OB Oughty Bridge MAC3 36m 23ch 24 July 1905 January 1984 Wadsley Bridge (WB)
OB Oulton Broad North NOL 22m 01ch 1901 24 February 2020 Colchester [new] (YL)
Oulton Broad Swing Bridge ESK 116m 02ch 1907 20 March 2005 Oulton Broad Swing Bridge [new]
Oulton Broad Swing Bridge [new] Renamed Oulton Broad Swing Bridge Operations Cabin 24 February 2020 ESK 116m 00ch 20 March 2005
OJ Over Junction SWM2 115m 53ch January 1953 2 June 1969 Gloucester (G)
OE1 Oxenholme No 1 Code used from 29 April 1973 CGJ7 ≈18m 45ch 12 May 1973 Carlisle (CE)
OE2 Oxenholme No 2 Code used from 29 April 1973 CGJ7 ≈19m 05ch 12 May 1973 Carlisle (CE)
OX Oxford DCL 63m 46ch 7 October 1973 7 July 2018last train; official closure 16 July 2018 Thames Valley Signalling Centre (OD)
BT Signals protecting Bicester London Road level crossing
DM Down main line automatic signals
DX Down Oxford line automatic signals
OD Code shown on some plans, believed never carried
UM Up main line automatic signals
UX Up Oxford line automatic signals
OR Oxford Road COL ≈189m 37ch Manchester Piccadilly (MP)
OS Oxheys CGJ6 ≈1m 30ch 3 February 1973 Preston (PN)
OY Oxley WSJ2 143m 14ch 30 March 1969 29 November 2010 West Midlands Signalling Centre (OS)
CS Oxley Carriage Shed WSJ2 ≈143m 17ch
O Oxmardyke Gate box: line controlled by Gilberdyke Junction (G) HUL1 16m 22ch 1901 23 November 2018last train; official closure 26 November 2018, delayed from 3 April 2018 York Rail Operating Centre (GH)
OX Oxmarsh Crossing BAR 106m 39ch 1959
OM Code reported but not seen on site
O Oxspring Junction PED2 0m 20ch 1933 20 May 1973 Line closed
CCM Oxted Original code phased out 1985-1987 SCU1 20m 32ch? 1896 July 1987? Oxted [new] (OD)
OD New code phased in 1985-1987
OD Oxted [new] SCU1 20m 31ch 11 July 1987