Dual Carriageway (some undivided) : 6.7 km (0 km by 2027)
The N20 connects Ireland's second largest city with its third largest - Cork to Limerick.
In the 2000s, when major upgrades of all trunk roads in Ireland were planned, this road suffered the unfortunate distinction of being, along with the N18 and the N9, the national primary route serving a city that was in most need of urgent attention.
However, the M9 and M18 have replaced those other roads, but still the N20 has not been improved.
The road starts on the quaysides of the River Lee in Cork City, following city streets out of the city.
An urban bypass of the suburb of Blackpool opened in April 2001, linking to the dual carriageway that runs as far as Blarney with its much-kissed stone.
From here, some parts of the road are in a 2+1 lane configuration, a rare sight in Ireland.
This takes the motorist as far as Mallow, which is not, incidentally, located in a marsh.
The upgrade of this section of the route will mainly consist of widening the existing road, since it is already up to a high standard.
Sadly the existing route goes steeply downhill in quality after this.
Mile after mile follows of poor quality, winding road which could only be described as a country lane.
This goes on for nearly 40 kilometres, passing through a bona fide chicane at Buttevant, the scattered town of Charleville, and countless small villages with bizarre names like Lackanalooha, Garrycummer, Imphrick, Shinanagh, Knockaunavoddig and Newtwopothouse.
The motorway replacement will be like stepping directly from the 19th to the 21st centuries.
Finally, the Croom bypass is reached.
In 2001 a grade-separated single carriageway road (rare in Ireland) opened which will form the basis of an upgrade in the future.
From here, it's a short hop to the N21/M20 junction and the motorway up to Limerick.
This section opened as dual carriageway in July 2001 and was redesignated motorway in August 2009.
It is Y-shaped with the M20 coming south from Limerick, then splitting with the N21 continuing southwest and the N20 veering south.
At the point where the M20 reaches the M7 Limerick Southern Ring Road, there is a large freeflow junction.
The entire route from the M20/N21 junction south to Cork will be replaced with a proposed M20 motorway.
This has been cancelled and reactivated many times but as of 2018 it is back on and included in the new National Development Plan.
It is anticipated to start construction in 2023 and open to traffic in 2026.
At the Cork end, a related project is the Cork Northern Ring Road, which will connect the new motorway from somewhere south of Blarney to north of Glanmire.
It is likely that the remainder of the road into Cork city centre will be renumbered at that stage, so the M20 will finish at the M20/Cork Northern Ring Road junction.
The M20 from Limerick to Cork is at Feasibility Study. It is cautiously pencilled in for completion by 2027.
Route options have been published.
These are mostly east of the existing N20.
Options for the potential rail improvements are on page 8 and include an upgrade of the existing rail lines, and the building of short segments of new line to make a shorter route.
The following update was taken from the NDP accompanying documentation and is courtesy of Boards.ie:
"The N20 road corridor options are currently being progressed with Public Transport (Rail) alternatives as comparators.
The scheme is currently at Route Options Selection stage where all the road and rail options will be considered, with the preferred transport corridor expected to be announced by the end of 2021 [note: now expected Q1 2022].
Subsequent to this, work on scheme design and environmental evaluation will be undertaken, in addition to the scheme Business Case, which is required under the Public Spending Code (PSC).
The scheme Business Case is expected to be submitted to DPER in early 2023.
Subject to its approval, the submission of the statutory documents for the project to An Bord Pleanála (ABP) will follow thereafter."
The preferred route corridor for the M20 Limerick-Cork motorway has been announced.
The details are on the official scheme web site.
The document showing the maps is here.
A TD has tweeted the announcement including a map of the proposed scheme.
The route corridor right now is 500 metres wide.
Since only a small part of that will actually be required, even if the current route appears over a particular property this does not necessarily mean that the property will have to be acquired.
The details of this will be worked out in future project phases.
A detailed description of the path the road will follow is here reproduced from the scheme brochure:
"The preferred option commences just south of the Blarney junction and remains largely online to maximise the reuse of the N20 until it diverges eastward near Mourneabbey.
Remaining to the east of the N20 it crosses the River Blackwater, the N72, the N73 and the River Awbeg as it bypasses to the east of Mallow and Buttevant until it converges with the existing N20 north of Buttevant.
It then remains close to the N20 until it diverges westwards near Ballyhea, bypassing to the west of Charleville, before re-joining the N20 south of Croom.
The preferred option reuses the N20 Croom Bypass and then diverges at Garranroe and
runs west of the existing N20 until it reaches its tie in point with the existing M20/N21 at Attyflin."
Additionally the preferred option for the rail improvements between the two cities has been announced.
The plan is to utilise the existing rail corridor but to eliminate the need to change trains at Limerick Junction and increase the linespeed.
A missing movement will be added at the junction to allow trains to travel between Limerick and Cork without the need for passengers to disembark and change trains.
Separately there was a long term plan to double-track the Limerick to Limerick Junction segment but seemingly this work will not take place at this time.