Signal box prefix codes

A (hopefully) comprehensive listing

'Boxes beginning I

Last update 1 December 2020

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
I Ibrox Junction AYR1 2m 5ch 1904 3 September 1967 Glasgow Central (G)
IG Temporary code until control passed to Glasgow Central.  Code possibly plain G
IC Ilford Carriage Sheds Also known as Ilford Car Sheds LTN1 8m 14ch 26 September 1949 29 March 1997 Liverpool Street [new] (L)
ICS
RIC Banner repeater signals
DE Down electric line automatic signals
DM Down main line automatic signals
UE Up electric line automatic signals
Ilford Car Sheds See Ilford Carriage Sheds
IS Ilford Station LTN1 7m 17ch 26 September 1949 24 August 1996 Liverpool Street [new] (L)
IY Ilkley Junction ILK2 211m 7ch 1913 11 July 1994 Leeds (L)
BC Immingham BSC Terminal 11 December 1988
Immingham East Junction BRI2 106m 34ch 12 October 1913 21 November 2012 last train;
2 December 2012 official
Immingham East Junction [new] (IE)
IE Immingham East Junction [new] Downgraded to Immingham East Token Exchange Point 30 December 2015 PYE2 0m 8ch 2 December 2012
S Immingham NCB Sidings KIL1 ≈104m 55ch
IR Immingham Reception Sidings BRI2 104m 30ch 6 October 1912
D Down line automatic signals
U Up line automatic signals
Immingham Token Exchange Point See Immingham East Junction [new]
IW Immingham West Junction KIL1 105m 5ch 25 March 1912
IM Code reported officially, but probably not carried
I Ingatestone Downgraded to gate box 19 October 1996: line controlled by Liverpool Street [new] (L) LTN1 23m 39ch October 1904
IG Unclear if this code carried
D Down line automatic signals
U Up line automatic signals
IH Insch Code used from 2002 ANI1 27m 47ch 1886
IK Inverkeilor Code used from 2002 ECN4 23m 10ch 1 March 1881
V Inverkeithing Central Junction ECN2 13m 20ch 8 November 1914 30 July 1979 Edinburgh (EV)
I Inverness Code used from 1987 HGL2
WCK
117m 77ch
0m 6ch
8 March 1987
HA Aviemore interlocking.  Code used from 26 March 2019
HC Carrbridge interlocking.  Code used from 26 March 2019
HD Dyce interlocking.  Code used from 17 August 2019
HE Elgin interlocking.  Code used from 17 October 2017
HF Forres interlocking (planned but HE used instead)
HK Kincraig interlocking.  Code used from 26 March 2019
HM Moy interlocking.  Code used from 26 March 2019
HN Nairn interlocking.  Code used from 17 October 2017
HS Slochd interlocking.  Code used from 26 March 2019
HT Tomatin interlocking.  Code used from 26 March 2019
MO Muir of Ord points indicators
IE Inverurie Formerly named Inverurie New Station.  Code used from 2002 ANI1 16m 79ch 10 February 1902 17 June 2019 Inverness (HD)
Inverurie New Station See Inverurie
IG Ipswich Goods Junction LTN1 69m 1ch 1912 5 April 1984 Colchester [new] (CO)
IS Ipswich Station LTN1 68m 58ch 1883 5 April 1984 Colchester [new] (CO)
D Down line automatic signals
Y Ipswich Upper Goods Yard IUP 18 August 1984 Colchester [new] (CO)
IS Irchester South SPC2 62m 8ch 27 June 1897 6 December 1987 Leicester (LR)
Ironbridge Power Station See Buildwas Power Station Control Room
V Ivybridge MLN1 235m 27ch ≈26 April 1895 8 December 1973 Plymouth (P)