Combine that image with the fact that 85% of everything we make, we export. Suddenly Ireland's dependence on imported goods and the importance of the port as an engine of economic growth become clear.

Despite huge growth in traffic . . . the amount of goods passing through the port increased by four million tonnes in 2006 to 29.2 million tonnes . . . this regular morning procession continues to run relatively smoothly. However, there are growing fears that this won't last.

According to the chief executive of the Dublin Chamber of Commerce, Gina Quin, the city's businesses are becoming increasingly concerned that the port is becoming another Dublin airport, "where longterm stalling on decisions has hit short-term capacity".

The problem is that the port is running out of space but its future development, like the ongoing wrangling over the airport's second terminal, has become a protracted political debate.

Last week, in the latest twist to the tale, Independent TD Finian McGrath claimed that Taoiseach Bertie Ahern had given a personal commitment that he would block the port's plans to reclaim 52 acres of Dublin Bay to provide it with extra room.

Meanwhile, there has been continuous speculation about moving the port elsewhere and selling off its current site to property developers, something Quin feels may have distracted people from its short-term development.

Quin said that while the chamber's members had no particular preference as to how the port should be developed, they were becoming increasingly frustrated by the political manoeuvring.

"The problem is that there has been no decision-making, just a series of reports and studies. We think the key thing is that we need someone with the courage to make a longterm decision, not one based on the length of a government, " she said. "Allowing these decisions to be put on the long finger is not helpful for the economy or business."

Although the Dublin Port Company has refused to comment on McGrath's claims, industry sources indicate that it is becoming frustrated by the delays to its plans.

"They're getting to the stage where they are squeezing the orange dry in terms of capacity and, without extra space, any investment in the port they would make would be sub-optimal, " said one source.

The main problem facing the port is that, although it has 650 acres, it lacks capacity for its container business, which represents around two-thirds of Ireland's container trade and is growing rapidly. The only way it can expand to cater for this trade, without leaving its current site, is by its stalled reclamation project.

Meanwhile, other ports are hoping to take advantage of Dublin's difficulties, including Drogheda, which is developing a deep-water port at Bremore, near Balbriggan, targeted partly at capturing the Irish import business of major multinational retailers.

The location has often been mooted as a possible new home for Dublin port but Drogheda port chief executive Paul Fleming said it was an entirely separate project, which aimed to complement Dublin port's facilities.

The first phase of the project, which is also backed by Treasury Holdings and is due to be operational by 2012, will have capacity for 10 million tonnes of cargo a year, most of which will be containers, and Fleming claimed there would be enough land for another 100 years of development.

The Bremore project has been given a boost in recent weeks by speculation that multinational drinks giant Diageo is planning to move Guinness production from Dublin's St James' Gate brewery to a site near Bremore for easy access to the planned port.

Fleming refused to be drawn on the identities of any of the port's potential customers but said talks with large importers and exporters had been going on for up to four years in some cases.

"We only deal with big names and most of our existing companies at Drogheda would be part of European, if not global, conglomerates, " he said.

Unlike the Dublin Port Company, which seems determined to continue developing in its current location, Drogheda port has decided to close its existing quay in Drogheda and sell the land for development once Bremore is built.

"Drogheda port was developed on an ad-hoc basis for over 100 years and it's not in a suitable location for modern shipping. There was no room for additional capacity and the port creates significant traffic problems for the people of the town, " said Fleming.

Drogheda port believes that the fact Bremore will not located in a town, like other Irish ports, will be a major attraction for potential users.

"One key factor is that the proposed outer orbital motorway route for Dublin will run from a point between Balbriggan and Drogheda, which will provide automatic linkage from Bremore to the rest of Ireland without have to get caught in Dublin city centre."

However, the Irish Exporters Association (IEA) seems unimpressed by the Bremore project and the notion of moving ports out of towns and cities.

"The vast majority of the world's ports continue to be slotted up against major urban conurbations, " said IEA chief executive John Whelan.

"Everyone goes for the shortest supply chain so the majority of goods going through Dublin port are used within the boundary of the M50 . . . you have to feed and clothe people in the city centre. No one wants to send their goods for there through Cork and then bring them up by truck, particularly with all the traffic congestion about.

"Bremore will help to take some of the additional strain once we get beyond 2010 but unless there is significant development in the site by the state, it won't be anything other the additional capacity for the Dublin region. It shouldn't be seen as a reason to delay development at Dublin port, " he said.