Construction of the M3 motorway in Co Meath is expected to begin next summer after a legal challenge was withdrawn yesterday.
After several months of discussions with the Department of the Environment, conservationist Vincent Salafia yesterday dropped his Supreme Court challenge to the proposed routing of the M3, near the Hill of Tara.
The agreement means that the State will absorb Mr Salafia's legal costs of €600,000 arising from his unsuccessful High Court challenge to the proposed route.
A spokesman for the NRA welcomed the settlement and said "significant archaeological work", which had been delayed for the past year, would now resume on the site. Construction work is expected to resume by May next year.
"This allows us to proceed after a significant delay . . . Now that it's resolved, we hope to proceed with archaeological work, and then construction work, as soon as possible," the spokesman said.
The NRA had previously claimed that delays in building the motorway were costing €1 million a week and had already reached €70 million.
Mr Salafia yesterday dismissed this "malicious" allegation and denied that his case had delayed work on the motorway. "The obvious truth is that my case has caused no delay in the M3, as excavations are not even due to end until early 2007. There has been no delay in construction and no injunction in place, by my own design."
He said the path was now clear for others to take legal challenges to the M3, one of which he understood was in preparation.
Mr Salafia also plans to petition the European Union to take legal action against Ireland for alleged breaches of EU law.
Fine Gael's road safety spokesman Shane McEntee said the dropping of the challenge was "welcome news for the thousands of hard-pressed commuters who have to get up before dawn to get to work or college".
He claimed the majority of people in Co Meath wanted the motorway built.
"The M3 is a controversial project but on balance it is essential for Meath and the country as a whole," he said.
The Department of the Environment declined to comment.