Railway line codes and bridge numbers

[Darrman]

As far as I can tell, every railway line in Ireland has a one or two character code, as seen on bridges and level crossings. Some former lines have codes too as CIE owns some bridges across disused lines/owned them as of about 2009 when the first street view images came in. I haven't seen these documented anywhere, so I'll post what I've seen and enquire if there's any more. Some codes appear to be meaningful and have what they likely stand for spelled out in addition to the route covered. I also did some research into bridge numbers as not every route begins with bridge number 1.

My sources include Irish Rail FOI requests (especially 136 and 137, linked here), Translink FOI requests (level crossings and bridges), and observations on Google Street View.

A: Athlone: Portarlington - Athlone
    Bridge numbers: 1 - 84
B: Belfast: Dublin Connolly - Border - (Belfast)
    Bridge numbers: 1 - 160 (continues in North)
B (EW): East Wall
Cork: Dublin Heuston - Cork - Cobh
    Bridge numbers: 1 - 438
CC: Conniberry Junction
CL: Collooney: Claremorris - Collooney
    Bridge numbers: 226 - 280
CN: Clonsilla - Navan: Clonsilla - M3 Parkway - (Navan)
    Bridge numbers: 284 - 296
Docklands: Liffey Junction - Docklands Station
    Bridge numbers: 218 - 233
DE: Dundalk - Enniskillen
    Line closed and lifted; bridge 5 remains in CIE ownership
E: Ennis: Limerick - Ennis - Athenry - Claremorris
    Bridge numbers: 1 - 202 (can't check Claremorris GSWR footbridge)
F: Foynes: Limerick - Foynes
    LB = Limerick - Ballingrane, BF = Ballingrane - Foynes
    Bridge numbers: 1 - 33 (LB), 1 - 17 (BF)
G: Galway: Dublin (Broadstone) - Mullingar - Athlone - Galway
    Bridge numbers: 1 - 173
    1-3 were Broadstone cutting, 172-173 noted as Galway-Clifden
H: Harbour: Waterford - Rosslare Harbour
    Bridge numbers: 124 - 227
J: (Macmine?) - New Ross - Waterford
    Bridge numbers: 349 - 470
K: Kingscourt: Drogheda - Navan - Kingscourt
    Bridge numbers: 1 - 50, 343 - 355
KW: Kilkenny - Waterford: Kilkenny - Waterford (used for bridges)
    Bridge numbers: 56 - 124
L: Limerick: Limerick - Waterford
    Bridge numbers: 1 - 187
LL: Dublin Loop Line: Connolly - Pearse (numbering continues into Rosslare)
    Bridge numbers: 1 - 51
M: Mayo: Athlone - Westport
    Bridge numbers: 679 - 799
N: Nenagh: Ballybrophy - Killonan Junction
    Bridge numbers: 1 - 94
NK: North Kerry: Ballingrane Junction - Tralee
    Bridge numbers: 34 - 114
O: Great Southern and Western Dublin Port Access: Heuston - Dublin Port
    Bridge numbers: 1 - 37
P: (Mallow? - Dungarvan) - Ballinacourty - Waterford
    Bridge numbers: 81 - 122
Q: Howth Junction - Howth
    Bridge numbers: 0 - 3
R: Rosslare: Dublin Pearse - Wexford
    Bridge numbers: 51 - 208, 244 - 343, 390 - 421
RW: Wexford - Rosslare
    Bridge numbers: 235 - 252
S: Sligo: Mullingar - Sligo
    Bridge numbers: 385 - 610
T: Tralee: Killarney Junction - Tralee
    Bridge numbers: 1 - 138
U: Mungret siding
V: Tralee - Fenit
    Bridge numbers: 1 - 14
W: Waterford: Cherryville Junction - Waterford
    Bridge numbers: 1 - 114
WW: Athy siding
X: Manulla Junction - Ballina
    Bridge numbers: 875 - 899
Y: Youghal: Glounthaune - Midelton - (Youghal)
    Bridge numbers: 1 - 37
Z: Silvermines siding

XBBP1: Clontarf Road White Light Crossing turns up in the level crossing list, but I'm not sure what BBP stands for or where it is.

NIR use a similar system to Irish Rail for their level crossings, but use an entirely numerical system for their bridges.

A: Antrim: Lisburn - Antrim
B: Bangor: Belfast Queen's Quay - Bangor
Dublin: (Dublin) - Border - Belfast GVS
L: L'Derry: Belfast York Road - Derry
P: Portrush: Coleraine - Portrush
R: Bleach Green Junction - Larne

1: Border - Portadown
    Bridge numbers: 161 - 242
2: Portadown - Belfast GVS
    Bridge numbers: 243 - 307
    1+2 (D) bridge numbers: 161 - 307
3: Belfast Central
    3 bridge numbers: 308 - 315
4: Belfast - Bangor
    4 (B) bridge numbers: 316 - 376
5: Belfast - Antrim
    Bridge numbers: 1 - 78
6: Bleach Green - Larne
    6 (R) bridge numbers: 416 - 465
7: Antrim - Ballymena
    Bridge numbers: 79 - 120
8: Ballymena - Coleraine
    Bridge numbers: 121 - 186
9: Coleraine - Portrush
    9 (P) bridge numbers: 253 - 264
10: Coleraine - Derry
    Bridge numbers: 189 - 221
    5+6+8+10 (L) bridge numbers: 1 - 221
11: Knockmore - Antrim
    11 (A) bridge numbers: 1 - 45
12: Greenisland - Monkstown
    12 bridge numbers: 23 - 27

The MGWR and NCC appeared to have bridge numbering for the whole network, and there's some unusual gaps in the DSER numbering. The GSWR just started every line from 1, and Bangor's bridge numbers seem to have been changed to follow up with the GNR main line. The M3 Parkway branch using what appear to be the original MGWR bridge numbers suggests to me Irish Rail have some historical bridge database lying around somewhere. Other things worth noting include:

• the remaining Foynes branch being labelled F, the numbering resets after Ballingrane, with the previous numbers continuing along the North Kerry,
• bridge numbering going from Mallow to Waterford to Rosslare and then from Wexford down again,
• what is nowadays known as the Western Railway Corridor continually counts up despite a code change at Claremorris,
• I is the only unallocated single-letter code (to my knowledge, I couldn't find any code for places such as the Limerick Junction bypass) south of the border.

[Barl]

Very comprehensive and informative list Darrman, thanks for putting it together. 

Just to add to it, the bridge numbers may not represent the actual number of bridges/culverts/underpasses on that section. For example, you can have OBC274 (an overbridge) then UBC274A, UBC274B and UBC274C - all culverts after OBC274 in the high mileage direction. 

The Limerick Junction loop line appears to be undesignated as you say, but there are no structures or level crossings on this stretch. The mileposts follow the Heuston to Cork numbering but are designated LN (Limerick North) to LW (Limerick West).