(bypassed routes in italics)
|Length:||62 km (39 mi)|
|Existed:||1994–2003 – present|
|Leixlip, Kilcock, Enfield|
The N4 road is a national primary road in Ireland, running from Dublin to the northwest of Ireland and Sligo town. The M6 to Galway diverges from this route after Kinnegad, while the N5 to Westport diverges at Longford town. The section of the N4 that is motorway standard is designated the M4 motorway.
The road is a dual carriageway from O'Connell Bridge, Dublin to Mullingar (including the motorway section). The section following the north and south quays in Dublin between O'Connell Bridge and Heuston Station has the River Liffey as its median. It continues as dual-carriageway with several signal controlled junctions until it intersects with the M50 motorway at Junction 7. This is also Junction 1 of the N/M4. The Liffey Valley Shopping Centre is located at junction 2. The road has three lanes and a bus lane in each direction between the M50 and start of the M4 at Leixlip. The N4 is the only one of the main inter-urban national routes whose dual carriageway section runs right into the city centre.
Heading west, the PPP motorway section (see below) ends west of Kinnegad, 5 km of road built to motorway standard (i.e. grade separated, no junctions and no median crossings) connects the M4 to an 5 km stretch of low-grade dual-carriageway with crossings which connects in turn to the Mullingar bypass. The Mullingar bypass is grade separated and to near-motorway standard. From Mullingar to Edgeworthstown, the road is wide single carriageway with hard shoulders. Between Edgeworthstown and Longford, there is a lower standard single carriageway road. Between Longford and Rooskey single carriageway continues at a higher standard. Dromod and Rooskey were bypassed in late 2007. This section of road consists of 3 roundabouts and Type 2 Dual Carriageway, i.e.: 2 lanes in each direction and no hard shoulder. The road becomes near-motorway standard dual carriageway again at Collooney, approaching Sligo town.
The section from Leixlip to west of Kinnegad is the M4 motorway. The first section of this motorway (Leixlip - Kilcock) was opened in 1994.
Under the Government announcement of the pilot projects on 1 June 1999 this project was to be assessed by the NRA for its suitability to be advanced as a Public-private partnership (PPP). Subsequently the project was included as one of the projects approved under Tranche II of the PPP Roads programme as announced by the NRA in June 2000. The project involved the construction of 39 km of motorway from Kinnegad to Kilcock and is an extension of the Kilcock-Maynooth-Leixlip motorway on the N4/N6 Sligo/Galway to Dublin route. The motorway by-passes the towns of Enfield and Kinnegad.
The PPP contract was awarded in March 2003 to the EuroLink Consortium (SIAC Construction Ltd and Cintra - Concesiones de Infraestrucutras de Transporte S.A.) and allows for them to collect tolls for 30 years from that date.
This tolled section from (Kilcock - Kinnegad) opened on 12 December 2005, and is the second most expensive toll road in Ireland (after the Dublin Port Tunnel). A toll of €2.80 (as of 29 June 2012) for cars is charged at a toll plaza just west of Kilcock and at smaller toll plazas at on and off ramps at Enfield. Between Enfield and Kinnegad no further access to the M4 is possible.
Eurolink operate this toll scheme, the first in Ireland not operated by NTR plc. From 2005 to 2007, Eurolink started to accept several tags issued by other motorways such as M1, M8, eTrip and Dublin Port Tunnel tags. Finally on 14 June 2007 NTR plc joined the Nationwide Electronic Toll Payment System introducing their popular EazyPass tags on the system and allowing all other toll plazas in the country (different from those owned by NTR plc) to accept them, meaning that each toll company's electronic tag will work on all toll roads in the State.
In the 1 July 2006 edition of the Meath Chronicle it was claimed that up to 10% of the €420 million road project had "to be ripped up and replaced" shortly after it opened due to rushed construction, however this cost would have had to be carried by the toll operators, not the state, as per the contract.
The bypassed former N4 road has been reclassified as the R148.
|This article is outdated. (December 2011)|
Currently, Junction 2a is the only motorway junction number in Ireland to have a letter, as it was constructed later between the present junctions 2 and 3, although a Junction 3A also exists on the N7 dual carriageway. New tourist signage at this junction refers to it as Junction 6, though the original directional signage has as of 2008[update] not been altered. As of March 2008 junction 1 has appeared on the recently erected sign at the newly reconstructed junction with the M50. Also maps on the National Roads Authority website for the Leixlip to M50 upgrade show new numbers for the junctions and count from the M50 westwards 
The Mullingar bypass also has a separate set of junction numbers beginning with J9.
|Westbound exit||Junction||Eastbound exit|
|M50 motorway : Dublin Port, Bray and all other routes (M50)||M50 motorway : Dublin Port, Bray and ALL OTHER ROUTES (M50)|
|Liffey Valley Interchange: Clondalkin, Liffey Valley Shopping Centre (R113)||Liffey Valley Interchange: Clondalkin, Liffey Valley Shopping Centre (R113)|
|Ballydowd Interchange: Lucan, Baldonnel (R136),||Ballydowd Interchange: Lucan, Baldonnel (R136),|
|Newcastle Road Interchange: Lucan, Newcastle (R120),||Newcastle Road Interchange: Lucan, Newcastle (R120),|
|Dodsboro||Lucan, Dodsboro, R835|
|Leixlip Interchange: Leixlip (R148) Celbridge (R403)||Leixlip Interchange: Leixlip (R148) Celbridge (R403)|
|Westbound exit||Junction||Eastbound exit|
|Leixlip West, Celbridge West R449||Leixlip West, Celbridge West R449|
|Maynooth, Clane, Naas||Maynooth, Naas|
|Kilcock, Clane R407||Kilcock, Clane R407|
|Enfield, Edenderry R402||Enfield, Edenderry R402|
|Enfield services||Enfield services|
|Kinnegad R401||Kinnegad R401|
|Galway, Athlone (M6 )||No access|
|End of motorway||Start of motorway|
|Road continues as N4 for Mullingar, Longford, (N5), Sligo|
On 28 August 2009 the Department of Transport implemented the second round of proposed reclassifications of dual carriageways as motorways under the Roads Act 2007. A short section of the N4, between Kinnegad (J12) and McNead's Bridge (J13) was affected by this. This extended the M4 westward by 6.8 km.
In July 2009 an upgrade of the section between the M50 junction and the Leixlip interchange was completed. On this section the road is three lanes in each direction, the median crossings have been removed and the junction with the R120 is now a fully grade-separated junction. Private accesses and some left turns remain preventing the section from being designated a motorway. The speed limit is 80 km/h.  There are now no signal controlled junctions on the N/M4 between Palmerstown and the Sligo throughpass.
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