Engineer's Line References (ELRs)

Northern Ireland

Northern Ireland Railways (Translink) appears to have two parallel code systems in use, one based on letters and the other on numbers. The alphabetical system is specifically referred to as Engineer's Line References.

Alphabetical system

It is notable that this system includes a change of mileage within one code (LBG).

ELR	Line name	Mileages	Datum	Notes
BCJ	Border to Central Junction	59.47 - 111.75	Dublin Connolly
BGD	Bleach Green to Londonderry	7.20 - 95.32	York Road via Greenisland (reverse)
BGL	Bleach Green to Larne	4.62 - 24.05	York Road mileage change
CGV	Central Junction to Great Victoria Street	111.75 - 112.44	Dublin Connolly
CJL	Central Junction to Lagan Junction	111.75 - 113.58	Dublin Connolly
CTP	Coleraine to Portrush	61.67 - 67.53	York Road via Greenisland (reverse)
CWJ	City Junction to Westlink Junction	0.00 - 0.18	City Junction
KJA	Knockmore Junction to Antrim	0.00 - 18.40	Knockmore Junction
LBG	Lagan Junction to Bleach Green	113.58 - 115.00; 0.00 - 4.62	Dublin Connolly; York Road mileage change
LJB	Lagan Junction to Bangor	113.58 - 126.06	Dublin Connolly

Numerical system

ELR	Line name	Mileages	Datum	Notes
001	Dundalk to Bangor	59.47 - 126.06	Dublin Connolly
002	Central Junction to Great Victoria Street	111.75 - 112.44	Dublin Connolly
003	City Junction to Westlink Junction	0.00 - 0.18	City Junction
004a	Knockmore Junction to Antrim	0.00 - 18.40	Knockmore Junction	route assumed
004b	Knockmore Junction to Lisburn	103.35 - 105.06	Dublin Connolly	parallel alignment to 001
005	Bleach Green Junction to Coleraine	7.20 - 61.67	York Road via Greenisland (reverse)
006a	Coleraine to Londonderry	61.67 - 95.32	York Road via Greenisland (reverse)	route assumed
006a	Coleraine to Portrush	61.67 - 67.53	York Road via Greenisland (reverse)	route assumed
007b	Belfast Central to York Road	113.58 - 115.00	Dublin Connolly
007a	York Road to Larne Harbour	0.00 - 24.05	York Road mileage change

Republic of Ireland

This system identifies bridges; there may be other systems in use for other purposes.

ELR	Line name
A	Portarlington - Athlone
B	Dublin Connolly - Border
B (EW)	East Wall
C	Dublin Heuston - Cork - Cobh
CC	Conniberry Junction
CL	Claremorris - Collooney
CN	Clonsilla - M3 Parkway - (Navan)
D	Liffey Junction - Docklands Station
DE	Dundalk - Enniskillen
E	Limerick - Ennis - Athenry - Claremorris
F	Limerick - Foynes
LB	Limerick – Ballingrane
BF	Ballingrane - Foynes
G	Dublin (Broadstone) - Mullingar - Athlone - Galway
H	Waterford - Rosslare Harbour
J	New Ross - Waterford
K	Drogheda - Navan - Kingscourt
KW	Kilkenny – Waterford
L	Limerick - Waterford
LL	Dublin Loop Line (Connolly - Pearse)
M	Athlone - Westport
N	Ballybrophy - Killonan Junction
NK	Ballingrane Junction - Tralee
O	Dublin Heuston - Dublin Port
P	Ballinacourty - Waterford
Q	Howth Junction - Howth
R	Dublin Pearse - Wexford
RW	Wexford - Rosslare
S	Mullingar - Sligo
T	Killarney Junction - Tralee
U	Mungret siding
V	Tralee - Fenit
W	Cherryville Junction - Waterford
WW	Athy siding
X	Manulla Junction - Ballina
Y	Glounthaune - Midelton - Youghal
Z	Silvermines siding