Detailed planning for Dublin's outer orbital motorway is to get under way next month, with the appointment of consultants to identify a route from Drogheda to Naas via Navan, Trim and Kilcock.
The new bypass for Dublin will broadly follow a National Roads Authority(NRA) indicative route going west from Drogheda, crossing the existing N3 between Navan and Kells and heading southwards to pass east of Trim before continuing south again to Kilcock where there would be an interchange with the M4.
From there it would continue to a junction with the M7, possibly at the existing M7/M9 interchange at Kilcullen.
The route is a little over 100km (62 miles) of motorway, with another expected 100km of ancillary roads and access for local villages and farms.
It will be the biggest road project built in the Republic and compares with the 60km (37 miles) of motorway and 50km (31 miles) of ancillary roads involved in the proposed €600 million M3 through Co Meath.
The NRA believes the road can be completed for just over €1 billion, a figure based largely on land costs significantly cheaper than recent Dublin area projects.
However, the authority says there "is absolutely no question" of the road being built out of its current multiannual budget which runs until the end of 2009.
Spokesman Michael Egan said the start date would be a matter for Government to decide. However, he added that the scheme would not be ready to go to construction for 3½ to four years.
The new bypass will not be completed as a C-ring around Dublin, however, as the Wicklow mountains prevent its continuation to the coast south of Dublin.
According to Mr Egan, the technical issues relating to building a road across the Sally Gap could be overcome, but the environmental issues were a different matter. "I don't think we will see it in my lifetime," he laughed.
Mr Egan said the authority was also studying the feasibility of the eastern bypass of Dublin which had been Government policy in the 1980s before being dropped.
The eastern bypass was intended to go from Booterstown in south Dublin, under Sandymount Strand and into Dublin Port where it would have connected with the Dublin Port Tunnel. It would transform the C-ring, M50 motorway into a full orbital route around the city.
Meanwhile, the NRA has confirmed it will seek a revised toll of up to €12 for cars using the Dublin Port Tunnel. There will be no charge for heavy lorries using the tunnel in keeping with the Dublin Transportation Office policy of keeping lorries out of the city centre.
Charges for cars will vary throughout the day and differ for inbound and outbound traffic at peak times. The NRA indicated a car rate of €3, set at 1999 values, and this would be about €6 when the tunnel opens next year.
Advertisements announcing an intention to seek changes to the rates will be published "imminently", according to the NRA, and a public hearing will be held, probably towards the end of September.