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) | |