The dubious solution of throwing roads at the car problem

So the eastern by-pass is back on the agenda, and nobody should be in the least bit surprised. Six years after being officially ditched, it has crept into Dublin Corporation's draft development plan.

This was inevitable; after all, there has been an engineering imperative to encase the city in a "motorway box" for nearly three decades, dating back to the flawed Dublin Transportation Study of 1971, and we should know by now that road engineers do not easily desert their pet projects.

The initiative to reintroduce it came from a cross-party triumvirate of councillors, the Lord Mayor, Senator Joe Doyle (FG), Deputy Eoin Ryan (FF) and Cllr Dermot Lacey (Labour), representing the Pembroke ward, which includes traffic-plagued Sandymount.

Their electorate used to be strongly opposed to the eastern by-pass, but the horrors of crossing Strand Road have persuaded people that the motorway would offer some relief.

Nobody, not even the National Roads Authority, knows what it might cost, but it's a fair bet that running a four-lane dual carriageway underneath Sandymount Strand and Booterstown Marsh will not come cheap. Just look at the escalating cost of the Dublin Port Tunnel, which would , and was always intended to, provide the northern leg of an eastern by-pass, and it seems quite evident that the price-tag will not be less than £500 million and perhaps a lot more.

One particular feature which would add substantially to the cost is the idea, canvassed by the three Pembroke councillors, that the motorway would be installed in a bored tunnel beneath Sandymount Strand to protect its priceless amenity. Unlike a "cut-and-cover" tunnel, this option has the beguiling advantage that all the work would be carried out unseen, as if by moles, though it would still leave vents sticking up through the sand at regular intervals.

The amenity represented by Sandymount Strand is important, and not just because it features in Ulysses; even the road engineers recognise that now. At one stage, they would have been quite prepared to drive the eastern by-pass right across the strand and through Booterstown bird sanctuary, hacking away everything in its path.

In the 1970s their original plans would also have meant demolishing more than 100 houses along the route, mainly on the north side.

It is easy to see the logic of extending the proposed port tunnel southwards, to connect up with the south-eastern motorway recently sanctioned by the Minister for the Environment. Instead of a C-ring represented by the M50 when it is finally completed, Dublin would get a full orbital ring road and thus a neat equation in engineering terms.

However, nobody seems to bat an eyelid about the enormous cost or to ask who or what precisely the motorway is meant to serve.

The eastern by-pass is not even included in the NRA's definitive Road Needs Study, published last July. This little-noticed study estimates that £6.14 billion (the figure is very precise) needs to be invested in further road improvements to national primary and secondary routes over the next 20 years. Yet even after all this money is spent, it admits that traffic will probably have reached saturation levels and may then, in the year 2019, require to be "attenuated".

Attenuated, indeed. This is engineering-speak for reduced, thinned out or made leaner, according to the Chambers Dictionary definition. With traffic levels growing by up to 6 per cent a year and forecast to continue rising with economic growth, it could be argued that saturation would be reached much earlier if there were no further improvements, but why not attempt to start "attenuating" traffic levels now, rather than after spending that £6.14 billion?

Of course, it would be difficult to do so in rural areas where there isn't even the semblance of a public transport service. In the cities and towns, however, it should be possible to attenuate the inexorable growth of traffic by restricting road space, through quality bus corridors and cycle lanes, for example, as well as the ad-lib availability of free car-parking space in parallel with much heavier investment in public transport. Nothing else is sustainable.

While there are undoubtedly many schemes on the NRA's shopping list which would be environmentally beneficial , notably providing bypass routes for towns still pummelled by heavy through-traffic, it beggars belief that the authority remains wedded to the outdated, even discredited, philosophy of "predict and provide". In other words, the task is to predict the level of traffic in, say, 2019 and simply spend the money on providing the road space to cater for it.

The NRA's bible in these matters is the US Highway Capacity Manual, not the latest thinking in the British government's white paper, A New Deal for Transport, published last July. Even though Tony Blair has balked at some of its more radical proposals, such as taxes on congestion and workplace car-parking, due to a fear of aggravating his party's recently acquired middle-class supporters, there can be little doubt that it can be seen as The Writing on the Wall.

The NRA, however, steadfastly holds to the belief that it's possible, even desirable, to continue throwing roads at the traffic problem, and it wants us to spend £6.14 billion on this dubious enterprise, not counting the cost of a full eastern by-pass for Dublin. Yet the same NRA had to admit last January that it didn't even know what type of traffic was going through the Glen of the Downs; in particular, whether it was national traffic or car commuters from north Wicklow.

What's also amazing is that huge sums of money can be bandied about in discussing major road schemes, £100 million here, £200 million there, and we'll need £6.14 billion at the end of the day, thank you very much. We do not seem at all fazed by such sums when they are being spent on roads, yet eyebrows were raised in certain quarters when CIE announced it would need £650 million to upgrade the railways, including disgracefully neglected Dublin commuter lines.

Nobody could deny that an adequate road network is required to cater for a burgeoning economy, but if it results in further dispersal of population and roads becoming ever more congested by far-flung commuters, will the NRA's £6.14 billion represent a sound investment?

As it is, the M50, even at a projected six lanes, looks likely to be clogged, not by traffic seeking to by-pass the capital, but by an army of motorists flitting between shopping "experiences" and business parks.

Whatever its proponents say, the eastern bypass would merely exacerbate a trend which already threatens to convert Dublin into a smallscale version of Los Angeles. Yet it now seems inevitable.