Irish power transmission systems operator EirGrid has identified an underground route option for its Grid West project, which would link the wind-rich west of Ireland to markets in the east.
The underground option, which would run from north-west Mayo to Flagford in County Roscommon, will now be compared with an already identified overland option for the project.
EirGrid considered several possible underground routes for the project before deciding on the Flagford option.
The work was carried out in consultation with local authorities in Mayo, Roscommon and Galway, as well as the National Roads Authority and other relevant agencies.
The proposal would see the underground cable mainly along local and regional roads from north-west Mayo, between Crossmolina and Ballina, down the east side of Lough Conn, north-east of Foxford and north of Charlestown, Ballaghaderreen and Frenchpark in County Roscommon to the Flagford substation area, south-west of Carrick-on-Shannon.
EirGrid also proposed localised changes to the preferred overhead route corridor option, following feedback from a previous round of consultation.
The changes involve undergrounding over 7km of the existing 220kV line into Flagford, as well as an alternative substation site or the option to underground lower voltage lines (110kV lines) into the proposed substation at Moygownagh.
EirGrid will write to landowners and homeowners affected by the preferred underground route option, as well as updating landowners within the emerging preferred overhead route corridor option.
In the coming weeks, the company will be contact stakeholders with details about how and where they can review this work, meet with the project team and provide feedback.
Following public consultation on the underground route, both options will be reviewed by an Independent Expert Panel appointed by the Minister for Communications, Energy and Natural Resources.
EirGrid chief executive Fintan Slye (pictured) said: "The work we are doing on both underground and overhead options will be brought together into a single report later this year.
"This report will be submitted first to the Independent Expert Panel and, subject to its approval, published for public consultation."