National Primary Route 3

Status : Complete

M3 Motorway Logo


Opened : 1992 - 2010

Motorway : 48 km
HQDC : 5.5 km
D2AP : 12.6 km
SC : 50 km (including Donegal section)

By far the most controversial road project ever built in the State, the M3 replaces the N3 route which links Dublin with Navan and the northwest of the country. In ancient times, this road lead to Tara, seat of the high kings of Ireland. Archeological evidence in has been uncovered that suggests that the route was paved with wooden logs covered with gravel, after remains were discovered in a bog. The N3 still runs past the Hill of Tara today, a major part of the country's heritage.

The N3 is unusual in that it is a single-digit national route but doesn't connect Dublin with any major destination of significance at its far end, a distinction it shares only with the N5, which goes from Dublin to the small west coast town of Westport. The N3 runs northwest out of Dublin and passes through a limited number of towns. The only ones of note are Dunshaughlin, Navan, Kells, Virginia, and Belturbet. The road then crosses the border into Northern Ireland where it becomes the A509 and the A46 after it passes through County Fermanagh's main town of Enniskillen. The route runs alongside the wonderful Upper and Lower Lough Erne, a large pair of lakes that bisect the county, before passing back over the border into the Republic for the final few kilometres to Ballyshannon and the coast. From here motorists can either turn left for Sligo and the south or north for the towns of Donegal.

With the Hill of Tara and the surrounding archaeologically rich area at its centre, upgrading the N3 to the M3 would always be difficult without causing significant disruption. This was exacerbated by the Government's choice to build the new route as a tolled motorway, with two collection points. This would surely make it an expensive choice for a potential car commuter.

The new route runs parallel to the old with the exception of the Navan-Kells run, where it skirts along the western side of the towns. Travelling north from Dublin, the route runs to the west of the existing N3 before switching over to the east for the run through the Tara and Skryne valley, the gap between the Hill of Tara and the Hill of Skryne. At the far end of the valley, it switches back over to the other side again. This is the section that is most contentious, and indeed during construction the remains of a large megalithic structure were found at Lismullen.

On the other hand, the M3 is a necessary high-capacity road in order to provide county Meath with a level of road infrastructure appropriate to a region so close to a major city. The existing infrastructure is shambolic. Indeed, a railway is certainly needed also. But whether the choice to run the road through the Tara valley and risk irreparably damaging Ireland's fragile past was a worthwhile one, only time will tell.

Update 12/07/2019: N3 Jct 1-4 M50 to Clonee Widening is at Design stage. The Dunshaughlin Motorway Service Area is planned but there has been no update since 2017. Virginia Bypass is in Feasibility Study.

Update 22/11/2020: The route options for the Virginia bypass have now been reduced to 5. Only 1 passes south and west of the town with the rest on the other side. There is a virtual meeting room displaying the options. This includes an introductory video.

Update 27/05/2021: An upgrade of Jct 2 Snugborough Interchange has begun. This will double the overbridge and replace the roundabouts with signal-controlled junctions. It will take 24 months to complete, so is expected by May 2023.

Update 03/06/2021: Regarding the Clonee to M50 widening scheme, the Emerging Preferred Option has been chosen: "Following the Stage 2 Assessment, DS2 Central Median Widening was selected as the Emerging Preferred Option. The existing wide central median will be minimised to form an additional running lane in each direction. Improvements are planned to the Inbound Bus Lane as a complementary measure alongside the DS2 Central Median Widening option."

Update 15/06/2021: The NTA are not supportive of the Clonee to M50 project, saying that the Greater Dublin Area Transport Strategy will be updated next year. This strategy is likely to recommend against schemes like that as they will just increase emissions.

Update 23/08/2021: The Emerging Preferred Route for the Virginia bypass has been announced. It can be found on the scheme website on the Publications page, and in the virtual consultation room.
Option C Variant 2 was chosen. This route continues the current end of the N3 north of Kells and runs alongside the N3 to the north. A spur will connect the new route to the old a short distance east of Virginia. It passes to the north of Virginia close to the town. West of the town, a spur road connects southwest to the Ballyjamesduff road. After that the new route will parallel closely the existing road before merging with it about 3.4 kilometres outside the town. The map of the route on this site has been updated.

Update 30/06/2022: The options selection reports have been released for the N3-M50 improvement scheme near Dublin. The option chosen was to widen into the median from 4 to 6 lanes.
The reports go into more detail on the project. Appendix C has detail on the junction improvements and closures of direct property accesses, and this document has the relevant maps. There are a few direct accesses to the road from adjacent properties. These will be rerouted to the local road network.
It is planned to keep the left-in-left-out at Parslickstown. This does not seem like a good choice as it is very close to the nearby grade-separated junction. It would have been better for the roads there to feed into the nearby grade-separated junction.
The document also mentions that they are still thinking of reclassifying Clonee-M50 as motorway.

Update 18/09/2022: Take a look at this timelapse video of the N3 Snugborough Interchange project. The concrete beams for the second bridge are lifted into position at night, as a series of long flatbed trucks queue up, each with 2 or 3 beams aboard. Closure of a carriageway was needed each time, but the bridge is now structurally complete and only needs paving and finishing works.

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Wikipedia page on this road

Pictures of this road, Videos of this road : Northern part of M3, Southern part of M3

Traffic Counts for this road


Origin M50 Junction 6, Castleknock, Dublin
Terminates Ballyshannon, Co. Donegal; including section in Northern Ireland (as A509)
Places Served Blanchardstown, Dunshaughlin, Navan, Kells
Routes Spawned -
Intersects M45 (Proposed Leinster Outer Orbital Road), M50, N52, N53


Section km Opening Date Standard
Jct 1-4 M50-Clonee (S Section) 5.5 1992-11-02 HQDC
Jct 4 M50-Clonee (N Section) 2.1 1992-11-02 M (from 2009-08-28)
Jct 4-5 Clonee/North of Kells (Part 1) 3 2010-06-04 M (from 2009-08-28)
Jct 5-10 Clonee/North of Kells (Part 2) 43 2010-06-04 M
Clonee/North of Kells (Part 3) 12.6 2010-06-04 D2AP
Belturbet Bypass 6.7 2013-12-13 SC
Jct 3 Mulhuddart Upgrade 0 2013-10-07 INTERCHANGE
Jct 2 Snugborough Upgrade 0 2023-05 INTERCHANGE
Dunshaughlin Motorway Service Area MSA
M50-Clonee Jct 1-4 Widening and Upgrade (5.6) M/WIDENING
Virginia BP ~14.6 ?