The idea of building a metro in Dublin is popular. People can imagine travelling through tunnels in sleek modern trains that glide into well-designed underground stations, far removed from the trials of on-street traffic congestion.
But popularity alone is not a reason to advance such a "big ticket" project as Metro North, which would link Swords to St Stephen's Green, serving Dublin airport, Ballymun, Dublin City University, the Mater hospital and O'Connell Bridge en route.
This is particularly true when the public, who will ultimately pay for it, are not being told what it will cost, even in ballpark terms. The likeliest estimate is between €3.5 billion and €4 billion, making it by far the most expensive public transport project in the State's history. Questions must also be asked about the priority being assigned to this project, as opposed to other schemes in the Government's €34.4 billion Transport 21 investment programme.
What Dublin needs, above all, is an integrated public transport system. The proposed metro would provide a modicum of integration by linking with the Maynooth suburban line at Drumcondra and the Sandyford Luas line at St Stephen's Green. The proposed second metro line, on a route parallel to the M50 linking Tallaght, Clondalkin, Blanchardstown and Ballymun appears to be notional.Thus, the only taste Dublin will get of a metro will be the line currently being promoted.
Of course, nobody could argue with the proposition that the city's heavily congested and rapidly expanding airport needs a rail link to the city centre. This could have been provided by building a spur from the Belfast mainline, at a fraction of the likely cost of Metro North. Meanwhile, the strategically most important project for Dublin in the Transport 21 programme - a rail interconnector between Heuston Station and Spencer Dock - is not scheduled for completion until 2015. This would serve the purpose of integrating all commuter rail services, linking with the Tallaght Luas line and the Kildare line at Heuston; the Sandyford Luas line at St Stephen's Green and the Dart line as well as the northern and southern commuter lines at Pearse Station.
The danger inherent in pursuing Metro North as a high priority is that it could swallow up so much money that there wouldn't be anything left to fund this vital rail link. Minister for Transport Martin Cullen has never explained the rationale for choosing the list of projects included in Transport 21, nor has he spelled out what they would individually cost. He needs to address those issues urgently, before taxpayers end up paying for a programme that, in effect, puts the cart before the horse.