Soaring land prices in south Dublin have been blamed for a £12 million shortfall which is holding up the start of work on the Dundrum bypass.
Dun Laoghaire-Rathdown County Council wrote to the Department of the Environment last month asking for the extra funding after it became clear that the projected cost of £21.5 million had more than doubled.
The bypass is due to overcome one of the worst traffic bottlenecks south of the Liffey and is seen as a vital feeder route for the soon-to-be completed Southern Cross motorway project.
The bypass was due to be completed before the opening of the motorway section.
Tenders had been submitted and a contract was about to be awarded when the extent of the shortfall became clear.
Now work on the project, which was to have begun immediately after the builders' August holidays, is on hold.
The Department of the Environment, which agreed a £10.5 million contribution in 1998, has confirmed it is considering the request for further funding and said it was seeking "clarification".
A council spokesman blamed rapidly increasing land prices and rising construction costs for the underestimation.
"Land prices in particular have gone through the roof," he said.
He denied the last-minute hold-up was an embarrassment for the council, saying that only in the last few months had officials been able to make firm projections of the cost.
Work could still start within weeks, subject to the extra funds being made available.
However, a South Dublin TD, Fine Gael's Ms Olivia Mitchell, said the delay was a result of "plain bad management".
She claimed it was obvious at least a year ago there was not enough money. The council was "embarrassed, and rightly so" at the situation.
Land values are understood to account for some £35 million of the £45 million cost now calculated for the project, with £8 million for construction and a further £2 million in fees.
However, much of the necessary land is already owned by the council or is being transferred to it by developers under the terms of planning permission, leaving the shortfall at £12 million.
Although the Dundrum bypass is designed to relieve traffic in the south Dublin village itself, it is also a vital approach road to the Southern Cross motorway route.
The motorway is expected to reach Dundrum next summer.
Whatever happens, the bypass is unlikely to be ready in time since it is estimated it will take 18 months to complete.
The council spokesman conceded there would be "very serious" traffic problems in the period between the arrival of the Southern Cross and the completion of the bypass.
Ms Mitchell said that when the motorway reached Dundrum traffic would be "disgorged on to the totally inadequate and already congested local road network".
"Every week's delay will add further to the congestion next year," she added.
