Laura Magahy, whose busy consultancy firm is providing executive services for the controversial Sports Campus Ireland project, believes that its showpiece stadium will be an "architectural gem". And judging by the list of superstar architects in the running to design it, there is every reason to suppose that she might be right.

But buildings can be gems and, at the same time, useless. The one that springs to mind is Arthouse in Temple Bar, a legacy of Ms Magahy's previous project - to create Dublin's cultural quarter. Nobody would dispute that this is a fine building, but what goes on there? What is it used for? Does anybody really know?

Huge question marks also hang over the Bertie Bowl. Is it credible, for example, that this edge-city stadium with seating for 80,000 spectators could be viable by staging just six major events a year? Croke Park, now being redeveloped at enormous expense, still costs the GAA a packet for maintenance - even when it is not in use.

Can Dublin, with its relatively small catchment population, sustain Stadium Ireland, Croke Park and Eircom Park? Or is the stadium at Abbotstown, as one cynical architect remarked, "Ireland's equivalent of the opera house in Manaus", in the middle of the Amazon jungle? Proof, if proof were needed, that we've lost the run of ourselves?

But the inherent unsustainability of the Taoiseach's grand project did not deter big-name architects from abroad queuing up for the kudos of designing it, including Jean Nouvel, architect of the Concert Hall in Lausanne, Dominique Perrault (Bibliotheque Nationale in Paris) and Richard Rogers (Centre Pompidou and Lloyds of London).

Others in the running for Stadium Ireland include Auer and Weber, Chaix and Morel, and Paul Andreu (in association with Murray O'Laoire). As already reported, Scott Tallon Walker is the only Irish practice on the list for the nearby 15,000-seat indoor arena, which also includes British architects Nicholas Grimshaw and Michael Hopkins.

However, Irish architects do feature strongly on a subsidiary panel for smaller projects on the 500-acre Abbotstown site. It is, of course, entirely coincidental that they include all the member firms of Group 91, the consortium involved in Temple Bar, as well as newer talents such as Tom dePaor, Hassett Ducatez and Bucholz McEvoy.

The 19 firms on this panel have a better chance of getting something built on the site, whether it's the golf academy, tennis centre, velodrome or whatever. But those on the panels for the stadium or indoor arena, having signed up with one or other of the seven international consortia tendering for the project, are in a sudden death play-off.

In neither case does the process involve a straightforward architectural competition. Because the contract for Abbotstown is being offered on a DBFOM (design, build, finance, operate and maintain) basis, other criteria will inevitably colour the picture when Sports Campus Ireland Ltd and its advisers come to assess the rival bids.

Design-and-build packages are not an ideal procurement method if the aim is to achieve "architectural excellence". They put the contractors in the driving seat, reducing architects to the role of making representations to secure a quality result; that's one reason why the Civic Offices in Tallaght are much less impressive than Fingal County Hall.

Sports Campus Ireland Ltd, which is chaired by former top civil servant Paddy Teahon, is aware of these pitfalls and has stressed the importance of architecture to each of the bidders. "What we want to do is to create something that's brilliant in architectural and civic terms," says Laura Magahy. "We're not interested in building crap."

Planning for the entire sports campus, which will cost the Exchequer at least £450 million (€571.5 million), which will include the relocation of State agricultural laboratories to Co Kildare, is proceeding at breakneck speed. Indeed, permission has already been granted by Fingal County Council for the £48 million (€60.96 million) Aquatic Centre, designed by British architects, S&P.

The draft master plan for Abbotstown, by German architects Behnisch, Behnisch & Partner, is quite coherent - at least in terms of fulfilling the brief. Essentially, it divides the site into three main zones, with the main sports facilities laid out alongside an artificial lake, natural parkland to the south and a still-notional "athletes' village" to the north.

The facilities are all linked by a covered walkway that weaves its way through the site. Though not yet designed, Ms Magahy says this will be more like the light tented structures used at the Seville Expo in 1992 than the hard, concrete walkways in Belfield. Walled gardens are another theme, to provide shelter for tennis courts, for example.

In the plan, a discreet veil is drawn over the volume of car-parking to be provided on the site. Only one such area is clearly indicated, whereas in fact parking is very extensive, with up to 7,000 spaces mainly on the surface and grouped around the proposed stadium, plus at least as many more on the capped Dunsink dump, across the M50.

Behnisch, Behnisch & Partner's plan played up to the brief's emphasis on creating a "flagship environmental project . . . in a sustainable and unique setting". They talked about visitors to Abbotstown being "immersed in flowing and intermingling spaces" with a green, open, healthy heart . . . nourished by "the energy of the flowing water".

BUT whatever about the environment created within the site, the real questions about this vastly ambitious project revolve around the impact of concentrating so many sports facilities on a site at the edge of the city. Even without an 80,000-seater stadium, this is highly questionable; with it, Abbotstown becomes a transport nightmare.

Even on weekends where there would not be, say, a rugby international in the stadium, it is likely to become a major traffic generator. For Sports Campus Ireland is envisaged as a "people's park", rather than just a sports concentration, which would attract hordes of families, turning it into a "destination attraction", in tourism terms.

It would have lots of bars, restaurants, shopping and leisure facilities, as well as a number of hotels. The indoor arena, some three times the size of the Point Depot, would obviously be used for entertainment events while the stadium would provide an ideal venue for huge rock concerts, which might also help it to pay its way in the world.

Stefan Behnisch, whose father, along with his partner, designed the 1972 Olympics site in Munich, must be accustomed to "edge-city" development; his firm has a branch office in Los Angeles, where the concept was invented.

He does not identify Sports Campus Ireland as unsustainable. "I would concentrate on making it work," he insists. "I like the site very much; one third of it is beautiful parkland. It is a great opportunity to realise a sustainable concept that's technically and architecturally right. For example, the whole site could be run on energy generated by wind turbines and methane recovery from the dump."

Mr Behnisch admits that he doesn't know Dublin very well, having visited the city "a couple of times". As winner of the master plan competition, he served on the jury that selected the panels of architects for individual buildings at Abbotstown. "It will be a new experience working with other architects designing the buildings," he says.

What Sports Minister Jim McDaid unveiled lately was Behnisch, Behnisch & Partner's competition-winning entry, not the final master plan. This still needs to be fleshed out so that the other architects have guidelines on what is required; for example, Stefan Behnisch wants the stadium to be "dug in", like the Olympic Stadium in Sydney.

Only two existing buildings are being retained - Abbotstown House itself, which he thinks would be "great as a resort hotel", and the barn-like State Laboratory, designed by John Tuomey in the late 1980s. Because this became something of an icon at the time, it is being kept, sitting incongruously in the middle of Abbotstown's "green heart".

Behnisch, Behnisch & Partner's commission extends to infrastructure, landscaping, lighting and street furniture throughout the site. It will also be up to them, in association with other consultants, to resolve the huge transportation question mark hanging over Abbotstown. Because unless this is done satisfactorily, the project could be a disaster for Dublin.