The school term begins in earnest on Monday - and with it, the inevitable increase in Dublin peak-time morning traffic. By the time the third-level colleges re-open and all those late summer breakers are back at work, it will be back to the grind of morning and evening commute.

Except that this year it will be worse - considerably worse. When work starts on the Dublin Port Tunnel in October, effectively shutting off the main M1 artery from Whitehall to the Airport, the knock-on effect on the city's already hard-pressed transport system will be considerable.

There is no question that the Dublin Port Tunnel should proceed and the Dublin Chamber of Commerce has been its greatest advocate. When it is open as scheduled at the end of 2004, it will take 20,000 cars and trucks a day off the city streets.

The tunnel will run from a portal on the M1 motorway at Santry to Dublin Port at East Wall, and will take port-bound traffic to its destination in six to seven minutes. The benefits to the city will be enormous. The ironic thing about this project - estimated to cost £350 million (€445 million) - is that if it had been planned and built with the same speed and efficiency as, for example the Tagus Bridge project in Lisbon, it would already be open to traffic. But sin scΘal eile.

The problem now is to cope with the disruption that work on the tunnel will inevitably bring. The first phase of construction will involve a cut-and-cover operation (digging up the road, to you and me) along the M1 from Shantalla Bridge to Collins Avenue, from where it will be tunnelled underground as far as Fairview. The Shantalla bridge will also be temporarily removed, creating considerable disruption to users of the old Swords Road.

For a city whose transport system is already the subject for students of chaos theory (if a bus stalls in O'Connell St, traffic will back up to Dorset Street within five minutes), the ensuing traffic problems could be enormous.

The route affected is not just one of the busiest in Dublin, it is one of the busiest in the Republic.

Dublin Airport is already handling 15 million passengers a year and growing. Some 10,000 people work in the airport complex. There is a continuous convoy of fuel trucks travelling from the fuel farms at Dublin Port to the Airport.

Business between Dublin and Belfast is - thankfully - at its highest ever level. Commuter traffic between the city centre and north Dublin, Meath and further afield is growing exponentially.

The Dublin Transportation Office has plans in the pipeline to cater for that demand, including an Airport Metro link and increased suburban rail services, but they will take many more years to implement. In the meantime, the immediate problem must be dealt with.

Dublin Chamber of Commerce has already put forward a number of workable proposals to the Director of Traffic's office.

These include public transport routings to the airport via the Malahide Road, greater use of the M50 for car traffic, the speedy introduction of the Swords quality bus corridor, park-and-ride facilities close to the Airport bus routes, and a dedicated north-south freight route, to ensure easy movement of goods between the port, airport and city.

A further proposal is to use the Malahide Road bus lane as a multi-occupancy vehicle lane. This type of route is used extensively in the US to cater for buses, other public service vehicles and also cars carrying two or more occupants. In the context of family groups trying to access the airport, this proposal is well worthy of introduction.

But this is more than just about traffic. There is a much greater agenda at stake.

The shakeout in the IT sector is already having a severe effect on employment in Dublin. There are likely to be further casualties. The losses so far are not inherently Irish problems - they are part of a global problem within the sector. Nonetheless, Dublin is at risk.

Already, the multinational sector has been among those businesses expressing the greatest concern at our creaking infrastructure. The twin problems of labour shortage and affordable housing for employees are inextricably linked to transport solutions. If rapid progress can be made in transport improvements, the existing problems of the multinationals in Dublin and its hinterland can be greatly alleviated. We must hold what we have.

We must also plan for future investment. While there will continue to be a shakedown in the existing IT industry, new sectors will emerge in time. Dublin must continue to make itself attractive as the location for that new wave. Development of transport infrastructure will be critical to that success.

If Dublin can successfully manage itself around the Port Tunnel construction, that will be a very good test case for future developments. Our competitors are watching.

Gina Quin is chief executive of Dublin Chamber of Commerce