Signal box prefix codes

A (hopefully) comprehensive listing

'Boxes beginning U

Last update 28 March 2024

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 ELRMileage Opened Closed Control to
U Uddingston Junction WCM293m 44ch 27 June 1937 18 September 1973 Motherwell (M)
UN Uffington PMJ12m 74ch 26 June 1909
U Uffington MLN166m 42ch 1897 3 March 1968 Swindon (SN)
DM Down main line automatic signals
UM Up main line automatic signals
UC Ufton Crossing BHL43m 39ch 14 February 1943 3 December 1977 Reading (R)
UJ Ulceby Junction Formerly named Ulceby South Junction BRI1100m 32ch 1910 30 December 2015 York Rail Operating Centre (CB, MB)
UY Code used with semaphore signals
D Down line automatic signals
U Up line automatic signals
Ulceby South Junction See Ulceby Junction
UN Ulverston Code used from 2008 CBC119m 47ch 16 December 1900
UC United Colliery WSJ2203m 56ch 9 August 1970 1 October 1974 ultimately Chester PSB (CR)
UCR Distant signals
UC Unstone Colliery Sidings TJC1149m 68ch 15 January 1972 Dore (D)
Uphill Junction MLN1138m 06ch 1884 29 January 1972 Bristol (B)
UM Upminster FSS215m 38ch 17 April 1995 Upminster IECC (UR)
D Down line automatic signals
U Up line automatic signals
UR Upminster IECC FSS215m 38ch 11 September 1994 (planned)delayed from 6 December 2019 Romford Rail Operating Centre (UR) (planned)
NL North London Line signals. Code used from 4 January 2011
UGF Ground frame controlled signals
UE Upminster East FSS215m 44ch UPG0m 05ch ? ≈1995 Upminster IECC (UR)
UW Upminster West FSS215m 15ch ? 6 February 1961 Upminster (UM)
UY Upney FSS28m 09ch 27 March 1961 Barking (BK)
M Upper Abbey Mills Junction FSS13m 61ch 1 May 1961 Fenchurch Street (F)
UH Upper Holloway TAH12m 76ch 10 November 1985
CCH Upper Warlingham SCU115m 30ch 10 March 1884 2 November 1985 Three Bridges [new] (T) and Oxted (OD)
U Upton Park FSS15m 37ch 1 May 1961 Barking (BK)
UN Urlay Nook Downgraded to gate box 25 November 2013: line controlled by Bowesfield (B) DSN17m 38ch 1896 11 March 2019 York Rail Operating Centre (B)
R Distant signals
US Usan Code used from 2002 ECN428m 48ch 6 May 1906 2 February 2010delayed from 28 January 2008 Montrose North (MN)
UH Usworth Code used from 24 April 1982 FEP17m 45ch 1898 1991
U Uttoxeter Two signals only. Last all-new mechanical 'box NSS16m 00ch 28 January 1981
UR Code used from 2 January 2008