Roads are the dominant form of transport in Ireland. They account for almost 90 per cent of freight traffic and almost 95 per cent of passenger traffic on the island.
Yet, while Northern Ireland has consistently invested in key "strategic corridors", the failure to develop the Republic's primary roads system - and particularly the absence of significant investment in the 1980s - has left the State's road infrastructure in a very poor condition.
The Department of Enterprise Trade and Employment has expressed concern that bad roads could hamper efforts to lure investment to the Republic.
The Operational Programme for Transport 1994 to 1999 aimed to prepare the Republic's national primary road network for completion by the year 2005, with all inter-urban primary routes to a standard allowing average journey speeds of 80 kilometres an hour.
But many of the planned schemes remain incomplete, while others have not even been started.
The National Roads Authority's development plan, published earlier this year, proposed spending about £6 billion between 2000 and 2019. But such is the urgency to tackle the backlog that the DKM Review of Transport Infrastructure Investment Needs almost immediately suggested that the bulk of the programme should be speeded up to ensure completion by 2005.
According to DKM, some £4.3 billion should be spent between 2000 and 2004 to clear the backlog of projects. With that cleared, spending between 2005 and 2009 would be £800 million, while the spend from 2010 to 2014 would be lower again at £505 million and the lowest period of spending from 2015 to 2019 at just £423 million.
That such "front-loaded" investment, as DKM calls it, should take place appears not to be in dispute. The social partners, the Economic and Social Research Institute and the Department of Enterprise, Trade and Employment have all spoken of the urgent need to get goods and people on and off the island with the maximum ease.
However, sources close to the National Roads Authority and the Department of Trade, Enterprise and Employment have admitted privately that there could be problems with such a plan. "It has often been said that a new road takes years to install. That is two years to build and eight years to get through the planning process," said one source.
Another cited the Kildare bypass, which has been delayed by environmentalists concerns for a snail which lives on the nearby Pollardstown Fen.
There are also delays with the N11 in Wicklow, where a group of eco-warriors have objected to the upgrading of the road as it passes through the Glen of the Downs nature reserve.
But even if the planning process could be reformed quickly and still remain equitable, there are questions over whether the State can call on enough construction companies to undertake the work.
As the DKM report notes, massive increases in expenditure "might not even be logistically attainable for the years from 2000, even if finance were not a constraint."
Contracts are put out to tender internationally, but most Irish road contracts are too small to attract large European companies.
One possibility is to group some contracts together in an attempt to attract foreign firms, but this could lead to further delays.
For possibly the first time, finding the money for large capital projects may be the least of our problems.
Tomorrow: In the final part of the series Tim O'Brien and Lorna Siggins examine the investment needs of the Republic's seaports