Signal box prefix codes

A (hopefully) comprehensive listing

'Boxes beginning Y

Last update 17 August 2025

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
YD Yalding PWS138m 19ch 1894 22 June 1986 Wateringbury (WB)
Y Yarm LEN3 23 July 1967 Picton (P)
Y Yarmouth Vauxhall 'Vauxhall' often omitted from name NAY18m 12ch RBY20m 29ch 1884 17 February 2020 Colchester [new] (YL)
Yate Main Line Downgraded to ground frame on closure BGL2119m 54ch 9 March 1886 19 October 1969 Yate South (YS)
YS Yate South Code used from 20 October 1969 BGL2119m 74ch 1 March 1908 8 May 1971 Bristol (B)
DC Down Charfield line automatic signals. Code used from 20 October 1969
UC Up Charfield line automatic signals. Code used from 20 October 1969
YW Yatton West Code used from 28 November 1971 MLN1130m 35ch ≈1875 29 January 1972 Bristol (B)
DM Down main line automatic signals. Code used from 28 November 1971
Yaxham NOE9m 41ch ≈1882 13 June 1965 To trainman operation
Y Yaxley ECM172m 55ch 6 August 1890 28 April 1973 Peterborough (P)
D Down direction automatic signals
U Up direction automatic signals
YJ Yeovil Junction BAE2122m 31ch 3 March 1909 12 March 2012 Basingstoke Signalling Control Centre (SE)
DM Down main line automatic signals
DUM Down and up main line automatic signals
UM Up main line automatic signals
YP Yeovil Pen Mill Code as stated on signalling plans WEY141m 22ch 22 February 1937
YPM Code used on signals
CU-D Yoker Proposed College interlocking City Union lines down direction signals. Code shown on plans for Larkfield link YKR2m 04ch 2 July 1989
CU-U Proposed College interlocking City Union lines up direction signals. Code shown on plans for Larkfield link
QL-D Proposed College interlocking Queen St Low Level lines down direction signals. Code shown on plans for Larkfield link
QL-U Proposed College interlocking Queen St Low Level lines up direction signals. Code shown on plans for Larkfield link
SL-D Proposed College interlocking Strathbungo lines down direction signals. Code shown on plans for Larkfield link
SL-U Proposed College interlocking Strathbungo lines up direction signals. Code shown on plans for Larkfield link
YC Craigendoran interlocking. Code used from 1992
YD Dumbarton interlocking. Code used from 1992
YF Finnieston interlocking. Code used from 1989
YH Hyndland interlocking. Code used from 1989
YS Sunnyside interlocking. Code used from 1991
YY Yoker interlocking. Code used from 1989
YYR Yoker interlocking banner repeater signals
Y York [IECC] ECM4188m 38ch 14 May 1989 27 December 2018 York Rail Operating Centre (CF, L, Y)
CF Former Church Fenton lines
L Former Leeds lines
S Former Stourton lines
YYN York Yard North stop boards (uncertain whether code used or carried)
Y York [PSB] ECM4188m 39ch 9 April 1951 11 May 1989✖or September 1989? York [IECC] (Y)
D Down direction automatic signals suffix indicated line, e.g. D3L Leeds lines, D3N Normanton lines
U Up direction automatic signals suffix indicated line, e.g. U2L Leeds lines, U2N Normanton lines
B York Rail Operating Centre Former Brocklesby signals. Code used from 30 December 2015 ECM4188m 15ch 30 December 2015
B Former Bowesfield signals. Code used from 11 March 2019
BD Barnetby to Doncaster section. Code used from 30 December 2015
BG Barnetby to Gainsborough section. Code used from 30 December 2015
BL Barnetby to Lincoln section. Code used from 30 December 2015
CB Cleethorpes to Barnetby section. Code used from 30 December 2015
CF Former York IECC Church Fenton lines. Code used from 27 December 2018
DE Dore to Earles Sidings section. Code used from 25 March 2024
DH Dryclough Junction to Heaton Lodge Junction section. Code used from 20 January 2018
DS Darlington to Saltburn section. Code used from 16 November 2021
GH Gilberdyke to Hessle signals. Code used from 26 November 2018
GM Former Greatham signals. Code used from 10 February 2021
GP Godwall Lane Junction to Potters Grange Junction signals (planned)
HB Holbeck Junction to Bradford signals. Code used from 23 October 2018
HG Hall Royd Junction to Greetland Junction section. Code used from 20 January 2018
HM Former Healey Mills signals. Code used from 20 January 2018
HU Former Huddersfield signals. Code used from 20 January 2018
K Former Kings Cross signals. Code used from 3 December 2018
L Former York IECC Leeds lines. Code used from 27 December 2018
MB Marsh Junction to Brocklesby section. Code used from 30 December 2015
MM Milner Royd Junction to Mill Lane Junction section. Code used from 23 October 2018
MS Meadowhall South area signals (for Sheffield Tram-Train operation). Code used from 6 May 2018
MW Middlesbrough to Whitby section. Code used from 16 November 2021
NF Norton-on-Tees to Ferryhill section. Code used from 10 February 2021
NS Northallerton to Sunderland section. Code used from 10 February 2021
P Former Pasture Street signals. Code used from 30 December 2015
P Former Peterborough signals. Code used from 28 August 2023
S Former Sheffield signals. Code used from 31 May 2016
SA Former Sheffield Aldwarke signals code assumed in use
SG Selby to Gilberdyke section. Code used from 26 November 2018
SL Standedge to Leeds section. Code used from 26 June 2023
ST Former Stallingborough signals
TG Thorne to Gilberdyke section. Code used from 26 November 2018
W Woodburn Junction area signals. Code used from 22 March 2021
WL Hertford North to Langley Junction section (former Kings Cross signals). Code used from 3 December 2018 with ERTMS test track. Control from Hitchin when testing taking place
WN Woodhouse Junction area signals. Code used from 22 March 2021
Y Former York IECC signals. Code used from 27 December 2018
YA Kings Cross area signals. Code used from 24 April 2021
YB Welwyn/Langley area signals. Code used from 21 February 2024
YD ERTMS boards (planned) (shown in Peterborough-March area on signalling plan)
YYN York Yard North stop boards
Y Yorkshire Main Colliery Downgraded to shunters cabin 30 April 1977 YMC (26 September?) 1986 Line closed
YYN York Yard North HOS0m 79ch 1902-1905 11 May 1989 York [IECC] (Y)
YYS York Yard South HOS0m 25ch 29 July 1962 11 May 1989 York [IECC] (Y)
YM Ystrad Mynach Named Ystrad South to 1892 CAR13m 33ch 1886 6 September 2013 South Wales Control Centre (CF)
Ystrad South See Ystrad Mynach