The project’s environmental impact report finds that even using the most pessimistic growth forecasts, the benefits of the motorway would outweigh its cost by two to one and deliver significant advantages to road users.

The report compiled in 2009 and published the following year considers three traffic growth scenarios up to 2015, all of which would deliver significant positive returns on the project now estimated to cost €800m.

Despite the report being six years old, its findings remain as relevant today, according to one of the country’s senior transport engineers.

Richard Bowen, senior engineer with the Transport Infrastructure Ireland, formerly the National Road Authority, said the analysis showed that, even in the “worst case scenario”, the benefits of the scheme were significant.

Should the project be granted approval the analysis would have to be re-run before an application can be made to Bord Pleanála for approval but the results would reflect those of the 2009 report, he said.

“The [cost-benefit analysis] is made up of costs, land, and construction primarily, and benefits which are broadly proportional to traffic flows along the route,” said Mr Bowen.

“Since 2009, when the environmental impact statement was prepared, both the costs and traffic flows will have decreased, though not necessarily in proportion to each other.

“The environmental impact statement was prepared in 2009 against an uncertain economic outlook and efforts were made to assess a worst case scenario for the cost-benefit analysis by using a ‘low-low’ traffic growth scenario.

“This still showed that the benefits of the scheme outweighed the costs by a factor of two. If, or when, a detailed cost-benefit analysis is re-run, the scheme should still provide a strong economic case for investment.”

Business groups have campaigned for years for a link between the country’s second and third cities.

Analysts suggest that the motorway could significantly improve the economic links between the two cities, delivering growth and developing the region as a counterbalance to the rapid growth in Dublin and its surrounds.

Ibec Cork regional director Peter O’Shaughnessy said the issue must be a matter of priority to allow the region to achieve its economic potential.

“With half a million people living within 10km of the proposed motorway, the crucial M20 Cork-Limerick project needs to be urgently progressed,” said Mr O’Shaughnessy.

“If delivered, this project can support economic recovery in the entire south-west and mid-west regions and will underpin the regional contribution to the national economy.

“The lack of a motorway is damaging connectivity and competitiveness of the region.

“The proposed mid-term review of the Capital Investment Plan this year should be used to channel windfall corporate tax gains to essential projects such as the Cork-Limerick motorway.”

The project was again shelved when it failed to be included in the Government’s €27bn capital plan late last year.