Work is to begin on a dual carriageway that passes a protected swan habitat after an environmentalist lost a legal bid to block the development.
Chris Murphy went to the Court of Appeal to challenge a High Court ruling upholding the proposed route of the A6 upgrade project.
The contested area focused on the middle section of the wider £160 million plan to dual part of the A6 between Belfast and Londonderry.
The controversial stretch is between Toome and the Moyola River at Castledawson, a route passing close to the shores of Lough Beg.
The scenic landscape of the area provided the inspiration for much of the late Seamus Heaney's poetry.
Mr Murphy contended there would be a negative impact on an internationally protected conservation area at Lough Beg that provides a habitat for migratory bird species.
He also claimed Stormont's Department of Infrastructure had not undertaken appropriate impact assessments.
He said the land earmarked for development provided foraging and roosting locations for Whooper Swans and argued alternative routes, to the south, would not have an adverse effect on the conservation zone.
Appeal court judges in Belfast rejected the grounds for Mr Murphy's case and dismissed his call for the matter to be referred to the European Court of Justice.
A spokesman for the Department for Infrastructure said the Appeal Court upheld the original ruling that the department acted correctly.
"Both judgements confirm the department's robust economic, engineering and environmental assessment procedures," he said.
"As a result of the judgement the department will commence construction of the Toome to Moyola River section of the scheme which had been delayed due to the legal challenge.
"The A6 scheme is fundamental in enhancing connectivity, improving journey times and unlocking the economic potential of the whole region.
"Local communities will also see economic and social benefits resulting in employment opportunities from a scheme of this size."