M8 motorway (Ireland)

The Glanmire Bypass opened as a 6.3 km dual carriageway on 3 April 1992, after a construction period of almost seven years, representing the first major improvement made to the Cork to Portlaoise corridor. Called for in the 'Land Use and Transportation Study' (LUTS) Report of 1976, the bypass replaced the older road through Glanmire village and was envisaged as part of broader strategic roads upgrade to service an expanding Cork City.[7] Other components of this plan, such as the N40 South Ring Road and the Jack Lynch Tunnel, were substantially delivered and operational by 1999. The Glanmire Bypass was built by multiple contractors at a cost of 45 million punts.[8] It was reclassified as a motorway in July 2009 and was officially incorporated into the rest of the M8 route on 28 August 2009.[9]

The Watergrasshill Bypass was the second section of grade separated dual carriageway to open on the Cork-Portlaoise route. It opened on 12 September 2003, at a cost of €144 million.[10] Built by Mowlem and Bowen in partnership, the seven kilometre route replaced a winding and narrow section of the older N8 (now the R639) through Watergrasshill and Sallybrook villages. The Watergrasshill Bypass was the cause of some controversy in October 2006 when its northern junction was incorporated into the tolled 'Fermoy Bypass' section of the M8, as, previously, it had been untolled.[5] As with the Glanmire Bypass, the Watergrasshill Bypass officially became a part of the M8 on 28 August 2009.[9]

Construction of the €48 million 6.7 km Cashel bypass began in May 2003 and it opened to traffic in October 2004 with a speed limit of 100 km/h.[11] Originally classified as a standard dual carriageway section of the then N8, the scheme was officially redesignated a motorway by Statutory Instrument on 17 July 2008. This change came into effect on 24 September in the same year and blue motorway signage replaced the green signage erected in 2004. In addition, the speed limit was increased to 120 km/h. The Cashel bypass opened initially with at-grade roundabouts at both ends. When the Cashel to Mitchelstown scheme opened in July 2008, the southern end of the bypass was fused with the northern end of that scheme by removing the at-grade roundabout and replacing it with a new extended dumbbell interchange. The same happened at its northern end when the Cashel to Cullahill project was built. The Cashel Bypass was built by Roadbridge Ltd.

Construction of this 17.5 km tolled scheme started in June 2004 and was completed on 2 October 2006.[12] This was the first stretch of actual M8 to open in the country (the Cashel bypass opened as standard DC in 2004 before its motorway redesignation in mid-2008). The section was built by Direct Route, who continue to operate and maintain it.[13]

Construction of this 37 km length of motorway started in May 2006.[14] It was fully opened with a 100 km/h speed limit on 25 July 2008, some 10 months ahead of schedule.[15] Twelve kilometres of the scheme had already opened nine months prior to this. This previously opened stretch, located between Cahir and Cashel, runs between junctions 9 and 10, and opened as a High Quality Dual Carriageway (HQDC) section of the then N8 with green signage. The green signage was replaced with blue motorway signage in September 2008 in preparation for the motorway redesignation changeover, which came into effect on 24th of that month.[16] The scheme was built by Roadbridge Sisk JV.

Construction of this 40 km stretch started in October 2006[17] and was opened to traffic on 8 December 2008, some seven months ahead of the target completion date.[18] Like four of the other M8 schemes, the section was originally to open as HQDC with green signage and a 100 km/h limit. However, due to its redesignation as motorway in September 2008 it opened with full motorway restrictions, appropriate blue signage and other standard motorway features (emergency telephones, etc.). The scheme was built by Roadbridge Sisk JV at a cost of €434 million.

Construction of this 16 km scheme started in December 2007. The section opened to traffic on 25 May 2009, some nine months ahead of the original target completion date.[19] Like the Cashel-Cullahill project, the Fermoy-Mitchelstown scheme was redesignated a motorway during its construction, having originally been envisaged as a HQDC.[20] It was built by Roadbridge Ltd. at a cost of €174 million.[19][21]

This section of the M8 was the penultimate part of the motorway to enter the construction phase, in June 2007. At 4pm on 28 May 2010 it was the final section of the Dublin-Cork interurban route to open. The contractor building the scheme was Portlaoise Joint Venture (PJV), which was acquired by BAM before the project's completion. The scheme drew national attention during the preliminary archaeological investigations in January 2006 when over 500 human skeletons from the seventh century were discovered at the townland of Parknahown just south of Cullahill.[22] A proposed local access junction, which would have been numbered '2' on the M8's junction numbering scheme, was eliminated from the final design by the Irish planning board to enable construction of full movement access between the M8 and the M7 at a future date if required.[23] The road is under the management of Midlink M7/M8 Ltd, and cost €491 million to construct.[24]

Transport Infrastructure Ireland (TII) is constructing motorway service areas at approximately 60-kilometre intervals along each of Ireland's interurban routes.[25] Under this plan, the M8 currently has three such areas. The first is located at junction 3, the second at junction 8 and the third at junction 14.[26] The Environmental Impact Statement (EIS) for the service area near Cashel was published in mid-February 2009,[27] while the Notice of the Compulsory Purchase of land for the service area was advertised on 31 August 2010. The service area at Cashel opened on 9 June 2011.[28]

The Manor Stone service area at Ballacolla, Co. Laois opened in 2015.

The EIS for the final service area near Fermoy was published in 2014. This service area opened on 30 March 2018.

Transport Infrastructure Ireland published a proposal to link the M8 at junction 18 with the proposed N40 'North Ring Road' for Cork city in late 2008. The proposed junction, which would be free-flow in both directions, would effectively convert the M8 between junctions 18 and 19 into one segment of the envisaged 360-degree ring road around Cork.[30]