M1 motorway (Republic of Ireland)

The Mary McAleese Boyne Valley Bridge carries the Drogheda bypass across the river Boyne.

Almost the entire length of the N1 has been upgraded to motorway standard and is designated the M1 motorway. It runs from the Junction 3 of the M50 ring road in Dublin, past Cloghran, Swords, Balbriggan, Drogheda, Dunleer, Castlebellingham and Dundalk before ending at Ballymascanlon north of Dundalk. It by-passes many towns and villages through which the N1 travelled.[1] The original N1 route now forms the R132.[2] At Ballymascanlon, it becomes the N1 dual carriageway and continues to the border with Northern Ireland. The motorway section of the N1 uses the M1 designation. Small yellow route markers along the motorway route also read N1.

The motorway was built in several stages as short disconnected bypasses, replacing the original N1 route. The first section opened (in 1983) was from Whitehall to Coolock Lane followed (in 1985) by the Airport Motorway between Whitehall and Dublin Airport, only the third section of motorway opened in the Republic. 1980s style direction signs were still intact on this route up until 2006. Part of this original M1 is now a spur to Dublin Airport, while another part between Whitehall to the Port Tunnel portals is now narrowed to two+one lanes (although still grade-separated) as a result of the Dublin Port Tunnel work.

There are toll fees for use of the motorway between junctions 7 and 10, the section which forms the Drogheda bypass. Work began in 2004 on a bypass of Dundalk, and was completed three months ahead of schedule in 2005, extending the motorway to just south of the border.

Construction finished in 2007 on a cross-border stretch of grade-separated dual-carriageway linking the northern end of the M1 with the A1 near Newry in County Armagh. This was opened to traffic on 2 August 2007. Its length is 14 km (8.7 mi), 4.6 km (2.9 mi) north of the border and 9.4 km (5.8 mi) south of the border. This allows traffic to flow freely from Dublin Port on motorway/dual-carriageway standard road to the Hillsborough Roundabout, located south of Lisburn.

A 120 km/h (75 mph) speed limit applies on most of the M1, the exception being a 100 km/h (62 mph) limit between Junction 1 and Junction 2 at Dublin Airport. The lower speed limit is credited to the much higher volumes of traffic on this stretch. Fingal County Council raised the limit on this section to 100 km/h (62 mph) in June 2022.

M1 northbound in County Louth

The M1 from the air, at its junction with the M50 near Dublin, Ireland

As of 2011 all junctions feature their number on road signs.

County	km	mi	Junction	Destinations	Notes
County Dublin			1	R 139 – Malahide M 50 – Southbound	Continues as M50 towards Dublin Port and city centre.
			2	R 132 – Airport
			3	R 125 – Ashbourne, Swords	Northbound entrance and southbound exit only.
			4	R 132 – Skerries, Rush, Donabate (northbound) Swords, Malahide, Donabate (southbound)
			Lusk Service Area
			5	R 132 – Balbriggan South (northbound) Rush, Lusk (southbound)
			6	R 122 – Balbriggan, Naul (northbound) Balbriggan, Skerries, Naul (southbound)
County Meath			7	R 132 – Julianstown, Drogheda (South) (northbound) Julianstown, Balbriggan (North) (southbound)	Stamullen
			M1 Toll
			8	R 152 – Duleek	Northbound exit and southbound entrance only.
			9	L 1601 – Drogheda, Donore (northbound) Drogheda, Donore, Duleek (southbound)	Toll at northbound entrance and southbound exit.
River Boyne			Mary McAleese Boyne Valley Bridge
County Louth			10	N 51 – Drogheda, Navan, Collon	Drogheda Hospital, Slane
			11	R 132 – Monasterboice	Northbound entrance and southbound exit only.
			12	R 169 – Dunleer, Collon
			13	R 170 – Dunleer	Northbound exit and southbound entrance only.
			14	N 33 – Ardee, Derry (N2)	Letterkenny
			15	R 166 – Castlebellingham, Tallanstown
			Castlebellingham Service Area
			16	N 52 – Dundalk (South), Mullingar	Ardee, Blackrock
			17	N 53 – Dundalk (Centre), Castleblayney	Crossmaglen
			18	Dundalk (North), Carlingford (R173)	Greenore, Ravensdale (R132). End of motorway, continues as N1.
			19	R 174 – Ravensdale	Northbound entrance and southbound exit only.
			20	Carrickcarnan, Jonesborough (B113)	Northbound exit and southbound entrance only. Exit sliproad crosses border. Continues as A1 into Northern Ireland.
1.000 mi = 1.609 km; 1.000 km = 0.621 mi       Incomplete access        Tolled       Route transition

The upgrade of the N1 is now complete in the Republic of Ireland, the first major route to be completely upgraded to motorway/dual carriageway standard (outside of Dublin city centre) as per the National Development Plan. The Northern Irish authorities have no plans to replace the A1 route (currently dual carriageway) with a motorway, although many junctions have now been grade separated. Currently, to drive from Dublin city centre to Belfast, one travels along the M1 (Republic of Ireland), N1, A1 and M1 (Northern Ireland).

The first official on-line motorway service area in Ireland opened on the M1 on 8 September 2010, located near Lusk. A second near Castlebellingham (M1 North service area) opened on 29 September 2010. Each location has northbound and southbound facilities, with no connection across the motorway between each side. Open 24 hours a day, they provide fuel and food and are of a design similar to those found in other European countries. The service areas are run by a consortium of companies known as Superstop.

As with other sections of Irish motorways which feature Variable-message signs, the M1 is also connected to an Intelligent transportation system providing real-time journey time information for motorists. The system works by recognising vehicle number plates at intervals along the motorway, and uses this information to calculate average vehicle speeds and hence travel times. Northbound, VMSs near Malahide and Balbriggan provide information on the journey times to the Drogheda (J7) and Dundalk (J16) exits. Similar signs southbound provide information on the travel time to Dublin Airport and the Dublin Port Tunnel.

Roadside art is funded under the Percentage For Arts Scheme where 1% of the scheme budget is allocated to roadside art with a cap of €63,000. The local authorities decide on a theme and are responsible for commissioning the work, usually by open competition.[3] There are several examples along the M1

• The Beehives. Three corbelled beehives on the Balbriggan bypass by artists Robert McColgan and Irene Benner made of cut stone in 2001 – Inspired by the tale of St. Molach, a beekeeper.[4]
• An Tarbh Donn, a three-metre-high (9.8 ft) bull on the Dundalk bypass by artist Micheál McKeown. Of metal mesh on a concrete base. Inspired by the Bull in the Táin Bó Cúailnge.[5]

Wikimedia Commons has media related to M1 motorway (Republic of Ireland).

• Roads in Ireland
• Motorways in Ireland
• National secondary road
• Regional road
• List of toll roads in the Republic of Ireland