Minister for Transport Martin Cullen has turned the sod on the new Mitchelstown to Cashel road upgrade.
The 32-kilometre section of the N8 forms part of the South West Corridor that links Limerick, Cork and Dublin.
The Cork-Dublin road is earmarked under the National Development Plan (NDP) for upgrading to motorway and "high-quality" dual carriageway standard. Work is due to be completed within three years.
The National Roads Authority awarded the contract for the road to Roadbridge Sisk in 2004.
Roadbridge Sisk has worked on a number of road-building projects, including the Boyne Bridge on the Belfast-Dublin road.
Speaking at the sod turning event today, Mr Cullen described the project as "one of strategic importance".
He said many people would gain from the road. "Together with other improvements for a new N8 / M8 this project will benefit many road users," he said.
"As the N8 Cashel to Mitchelstown forms part of the South West Corridor that links Limerick and Cork and Dublin, it will benefit commercial and tourism sectors as well as cutting travelling times and reducing congestion.
"In addition, it will reduce traffic volumes going through local villages, giving the villages back to their people and improving road safety."