Sceptics who thought Luas might never happen must be somewhat taken aback by the extent of the construction works now under way. But there is still a huge question mark over the architectural treatment of scars to the urban tissue being inflicted by the demolition of buildings along the light rail routes.

Precisely the same issue arose in the 1970s and 1980s when Dublin Corporation's road engineers drew lines on maps, consigning whole streets to oblivion without any notion of what might be built alongside new dual carriageways, such as the one that hacked its way through Clanbrassil Street.

With Luas, it was all supposed to be handled much more sensitively. Urban design framework plans were prepared by the project team's architects and appended to the 1998 environmental impact statements (EISs) on the Tallaght and Sandyford light rail lines, with graphics showing notional architectural treatments.

These were required, in particular, for areas where the streetscape would change as a result of the Luas project - notably Arran Quay Terrace, off Smithfield, as well as Mary's Abbey, off Capel Street, and the landmark corner of James's Street and Bow Lane West, where the Tallaght line will swing into Steevens's Lane.

The two buildings that stood at this important junction - the Barn Owl pub and an adjoining bookmaker's office - may have been only three storeys high, but they had been consciously designed around 1900 to address the triangular public space in the foreground, recently repaved to emphasise its civic importance.

Alan Mee, a former project architect for Luas, designed a six-storey "bookend" building for the reduced site. A diamond-shaped sliver in plan and elevated over an open ground-floor arcade, it was unashamedly contemporary and provoked diametrically opposed views. But at least it suggested a potential solution.

Both of the pre-existing buildings have just been demolished, creating a very visible scar in the streetscape, and yet the only explanation of what is going on consists of a crude yellow billboard advertising Luas construction works and apologising for any inconvenience caused by the closure of Steevens's Lane since last November.

Jim Quinlan, the Luas project architect, is acutely aware of the open wound on the corner of James's Street and he has secured agreement to hold an open architectural competition to find a suitable scheme for the site, now somewhat larger because of the acquisition of property to the rear. It will be fascinating to see what emerges.

It is now too late, apparently, to change the alignment of Luas at St James's Hospital where the Tallaght line will now snake around the boundary rather than run right through because of reactionary opposition from the hospital's board. And the possibility of reopening the filled-in canal to James's Gate is also severely compromised.

As for other "crunch points" along the Luas route, Mary's Abbey is among the most problematic because the light rail legislation only gave CIE the power to acquire sufficient property to meet the "technical engineering requirement" - in other words, just enough to make room for the light rail trackbed, tram stops and new footpaths.

Though it did manage to acquire the very prominent building at the Capel Street corner, where a four-metre setback is needed, what will happen along the south side of Mary's Abbey is that the front portions of all the buildings will be demolished, leaving a sadly saw-toothed arrangement of new and probably temporary facades.

This would be a disaster in urban design terms and could be averted only if agreement can be reached with the various property owners on a more comprehensive approach. And some of them, particularly those in the wholesale fruit and vegetable trade, regard Luas as an inconvenience rather than a positive addition to the area.

Residents of Arran Quay Terrace are even more fed up. Though the Luas project team has planning permission to replace their artisan homes with a more appropriately-scaled scheme, in which they are all entitled to be re-housed, this is now in jeopardy because a hitherto-undiscovered lessee is seeking significant compensation for one property.

Another danger facing the project is penny-pinching. Because of its inflated cost, there may be a temptation to cut back on really important elements such as landscaping and street furniture, despite firm pledges earlier on in the tortuous Luas saga that these would be of the highest quality. Such a temptation must be resisted.

After all, nobody is going to see much of the groundwork currently under way, such as the diversion of utilities from the trackbed, after it is finished. What they will experience, however, is the quality or otherwise of tram stops, ticket machines, paving, handrails and so on. And much of the image of Luas will depend on how they look.

The original EIS contained a substantial contribution by landscape architects Mitchell and Associates on how the light rail system would be integrated into city centre streets. Unfortunately, the Government flunked that issue in May 1998 with its cowardly decision to go underground, in the face of a report by independent consultants W.S. Atkins.

Nonetheless, Luas will run on-street along much of its alignment and as much care will be needed to install it in, say, Abbey Street or Harcourt Street as in Dawson Street or Westmoreland Street, as intended before Ministers lost their nerve. So the fine detail of how this is to be done remains one of the critical issues in planning for Luas. One of the issues that arose in the early stages was whether CIE's remit merely involved providing a new transport system, with little or no reference to urban design. Or would it go much further in emulating Strasbourg and other French cities by using the installation of a light rail system as a lever to lift the overall environment?

In that context, it is surprising that the Luas project team has left itself open to be bracketed alongside the road engineers of old by demolishing buildings without having "ready-to-go" plans to replace them. And it's not as if there wasn't enough time to do this - Luas has been kicking around, in one version or another, for at least six years.

Jim Quinlan insists that the commitment to quality remains intact and he points out, for example, that Cormac Allen's original design for a dramatic suspension bridge at Taney Road in Dundrum has been changed only in detail by consulting engineers Roughan and O'Donovan. He is also looking at architectural lighting for this landmark structure.

Luas is the largest public transport infrastructural project in Dublin's history. If it was being done in France, there would be fanfare and a sense of celebration as the work proceeds. Crude "men at work" signs are simply not adequate to generate public awareness and appreciation of what this new transport system will mean for the city.