That Dublin is at its most critical crossroads for 200 years there can no longer be any doubt. The future of the city and its hinterland - indeed, of the Republic as a whole - will be determined over the next 10 years. And we will only have one stab at it because, in 2011, population growth is expected to level off and then decline.
The population of the greater Dublin area, which includes Meath, Kildare and Wicklow, is growing more than twice as fast as the rest of the State.
If these trends continue, it would account for more than half of the State's population by 2047, according to Brian Hughes, lecturer in urban economics at the Dublin Institute of Technology.
Based on the assumption that the Celtic Tiger boom is sustained, even at more manageable economic growth rates, he has calculated that the region will have a population of 1.9 million in 2011 - significantly more than the current planning target - and that we may need to produce up to 30,000 new homes per year to accommodate it.
We could, of course, continue travelling down the same road by allowing the capital to sprawl out over the countryside, gobbling up some of the best agricultural land in Ireland. Or we could attempt to consolidate the existing built-up area by developing housing at higher densities, especially in areas close to public transport routes.
Just as we are still living with the legacy of the Duke of Ormonde and the Wide Streets Commissioners, future generations of Dubliners will long be living with the physical shape of the city we leave to them. Thus, the course we choose to follow in catering for the current surge in population is of overwhelming importance.
Almost everyone involved in planning is nervous about what may happen; indeed, many anticipate chaos for the next few years as we feel our way towards a more environmentally sustainable path of development. They point to the fact that a fairly chaotic edge city is in the making along the crooked spine of the M50.
Office parks, industrial estates and shopping centres are increasingly locating in its catchment area, creating a counter-magnet to the city centre and a whole new pattern of travel, mainly by car. No longer are commuters driving from a suburb to the centre, but criss-crossing the wider metropolitan area from one suburb to another.
New and improved roads are also generating more dispersed housing development, still being built at unsustainably low densities, whatever the Government guidelines may say. The standard remains a two-storey, semi-detached, three-bedroom house with front and back gardens and off-street parking for at least one car.
Dubliners used to complain that the city was being over-run by culchies. Now, many can no longer afford to buy homes in their own city and little bits of Dublin, in the form of suburban housing estates, are springing up on the outskirts of Carlow, Gorey, Mullingar, Portlaoise and other towns way beyond the traditional commuter belt.
The massively accelerated roads programme in the new National Development Plan (NDP) is bound to increase this trend, because it will make many of the outer Leinster towns even more accessible to Dublin. These new dormitories will continue to offer cheaper housing options, but at the cost of thousands of hours of sitting behind a steering wheel.
The National Development Plan's £1.58 million for public transport in the Dublin area is a belated recognition that the city's horrendous traffic problems cannot be solved merely by building more roads. However, there is no indication that the Government fully appreciates the crucial connection between transport and land use in determining how a city develops.
It was the inauguration of the Kingstown railway line in 1834 that allowed Dublin's upper-middle classes to colonise Merrion, Blackrock and Dun Laoghaire, just as the Harcourt Street line opened up Dundrum, Foxrock and Carrickmines; the old tram lines did the same for Rathmines, Rathgar, Churchtown and Clontarf.
Yet the NDP is depressingly tentative about, for example, re-opening an inland rail link between Dublin and Navan. If the Government truly recognised the land use and transport equation, it would move to finalise an alignment for this route within the next 12 months so that housing development, in particular, would gather around it.
Similarly, why are we only "evaluating" the possible introduction of commuter rail services between Cork and Middleton and Limerick and Ennis? Limerick has no less than four railway lines running into it and no commuter service on any of them. If a commitment were made to provide such services, Limerick would be set on on a sounder path.
Within Dublin's inner city, the most important decision revolves around a new cross-river rail link to bypass the loop line. If this proceeded as a simple connection between the existing Spencer Dock railhead and a new Dart station at Barrow Street, it would only serve to reinforce the south-easterly drift of the city's centre of gravity.
However, if the strategic connection is made underground between Spencer Dock and Westland Row, continuing on to Heuston Station via St Stephen's Green, Dame St, Wood Quay and Watling St, and then on around the north side via the little-used Phoenix Park tunnel, Dublin would acquire a "circle line" to knit the city together.
This highly desirable scheme, a brilliant piece of lateral thinking in its own right, is one of the key options being considered by consultant engineers Ove Arup and Partners in their review of suburban rail services for CIE.
The cost is estimated at £300 million - coincidentally, the contingency figure allocated in the NDP to put Luas underground.
THE latter plan was hatched by the Cabinet in May, 1998 and would involve building a tunnel from St Stephen's Green to Broadstone. It is a barking mad idea because it would do absolutely nothing to increase the capacity of Luas and also completely ignores the main spin-off of an on-street light rail system - its extraordinary ability to civilise a city.
The fact that the Cabinet adopted the underground "solution" against the advice of its own independent consultants, WS Atkins, simply underlined the extent of its craven capitulation to the car lobby, which still believes that there is something inherently wrong with the notion of taking road space away from traffic and giving it to public transport.
Remember the hysteria it whipped up in advance of the introduction last autumn of the Stillorgan Quality Bus Corridor? The AA, which was to the fore in that campaign, became uncharacteristically silent when the first results showed that bus passenger numbers had more than doubled and the new service was even attracting plenty of "suits".
What Dublin needs is much more of the same - not just speedy implementation of the remaining QBCs but also an expansion of the Luas network to serve Ballymun, Clondalkin, Docklands, Finglas and other parts of the city. When Dubliners see the Tallaght line running in 2003, the clamour to extend Luas will become unstoppable.
Including QBCs, the Circle Line, Luas, new rail links to Dublin Airport and Navan and upgraded services on DART and other suburban lines, Dublin will have something it doesn't have at present - a public transport system - and the goal must be to ensure that as many people as possible are within walking distance of some element of it.
Of course, with increasing prosperity, there will be a lot more cars. But we will have to learn to make the distinction between car ownership and car use, just like many of our fellow Europeans. Much more reliable public transport and more sophisticated traffic management measures, including electronic congestion tolls, will help to change our ways.
Developing new residential areas at higher densities with a more varied range of housing types in close proximity to public transport modes is another imperative. Dublin Corporation's action plan for Pelletstown, off the Navan Road, shows the way in proposing to develop an urban neighbourhood on the city's last piece of farmland.
The Government must also understand that a laissez faire approach to the development of greater Dublin will inevitably turn it into Brian Hughes's envisioned "city-state of the 21st century", with more than half of the population living there. Its failure to identify alternative growth centres in the NDP indicates that it has no such understanding.
With the promised National Spatial Strategy at least two years down the road, we do not yet have any map of the Dublin and the Ireland we are destined to create, for good or ill, over the next decade. We have no vision other than to keep things going, more or less as they are, muddling along like the Government's Millennium Committee.
As for where all the money is to come from to pay for the much-needed public transport infrastructure, the State's coffers are still loaded even after the biggest-ever give-away Budget. As the Taoiseach said last August: "For the first time in our history, we are able to decide what we want and go out tomorrow and pay for it."
The importance of those decisions on how we invest our new-found wealth cannot be over-stated. An awful lot of money is to be spent over the next seven years; if not invested sensibly, it will do an awful lot of damage. "Bad projects are still bad projects," as the ESRI said. Fast-tracked or not, we have just one opportunity to get things right.
Frank McDonald can be contacted at fmcdonald@irish-times.ie