Dublin's C-ring motorway, two southern sections of which are yet to be completed, is to be increased in capacity from four lanes to six, according to the National Roads Authority (NRA).
The NRA said economic prosperity had brought an unexpected growth in traffic. It had been expected that two lanes in each direction would meet capacity until the year 2011.
Improvements to the "orbital" between Dublin Airport and Shankill are to be overseen by Dun Laoghaire-Rathdown County Council, which will now appoint design consultants at the request of the NRA.
Dun Laoghaire-Rathdown is embroiled in a court challenge to the final leg of the C-ring, the South Eastern Motorway between Ballinteer and Shankill, from land-owners who are unhappy with aspects of the proposed road.
Consultants have been asked to improve the capacity of the motorway because of traffic congestion. The decision will result in fresh plans for the South Eastern Motorway, before a sod is turned on the existing scheme.
Dublin's C-ring has been planned for more than a decade, and its present four-lane construction was expected to be sufficient to cater for use up to 2011.
However, Mr Michael Cahill, a spokesman for the NRA, told The Irish Times yesterday that the consultants' brief would be to increase capacity in any way they can. "Extra lanes and the removal of the N7, N4 and M1 traffic are obvious improvements in capacity, but we will also be asking them to consider what else might be done." The consultants will also consider a second Liffey bridge at the West Link above the Strawberry Beds.
A number of junctions on the Cring with other major radial routes are also to be redesigned to separate Dublin's orbital traffic from the national radial routes.
Mr Cahill said the design of the N7 Red Cow junction was such that it would be possible to take the N7 traffic over the motorway on a new bridge, as was done with Sligo traffic on the N4 and the M1 at the airport. "At the moment these interchanges slow things down considerably, and there are foundations already in place for a second bridge at the Liffey crossing, so that, too, would be an obvious advantage."
Mr Cahill added that the increase in traffic was something that could not have been predicted when the route was originally designed. "The motorway was the springboard that gave rise to the industrial successes around Belgard and Sandyford, but nobody could have predicted the Celtic Tiger," he commented.
