By Mike McKimm BBC Northern Ireland environment correspondent

When the new Westlink opened in 1983, it was almost instantly overwhelmed with traffic and some saw this as a token of its success.

But the endless jams showed a remarkable lack of foresight, an inability to listen and learn from the experts and that the focus of attention in 1978, when the work started, was quite clearly elsewhere.

The Westlink, at the edge of west Belfast, was built to link the two key motorways and draw traffic away from the centre of Belfast.

The public inquiry, starting in Belfast on Tuesday, will hear of a need to widen the Westlink and part of the nearby motorway to three lanes as a necessity to handle the additional volume of traffic.

It is planned that two roundabouts, which are serious bottlenecks at peak times, will be replaced by two flyovers.

Parts of the road are to be lowered to keep traffic noise to a minimum in what is a major residential area.

Curiously, at another public inquiry in Belfast in 1977, the case put forward was for a three lane system, lowered to keep the noise down and complete with two flyovers to prevent bottlenecks at roundabouts.

'Instant jams'

But despite warnings at the time, much of this was abandoned.

The result when the system was opened in 1983 was instant traffic jams. There was simply too much traffic wanting to use it.

Now almost 20 years later, having learnt from the mistakes, it has been decided to revert to the original plans.

But the traffic flow has dramatically increased and it is unlikely this system could ever be engineered to cope on its own.

This public inquiry will hear of plans for an extra lane in each direction, but probably dedicated to buses and lorries.

Interest groups

Representatives from the Department of Regional Development will explain how critical it is for the road to be developed.

Even organisations like Friends of the Earth have backed off a little in their ardent opposition to the development of the route.

The environmental lobby group wants a lane to be dedicated to public transport and heavy freight but with no extra lanes being added.

In other words, squeeze the motorist onto public transport.

They do have a considerable argument behind their rationale.

In linking the M1 motorway to the M2, the Westlink effectively gives access to Belfast Harbour, Northern Ireland's main port.

Port impact

It is being slowly stifled by the traffic jams on the Westlink and lorry drivers from the west of Ireland have started to give Belfast a miss, favouring instead the expanding port of Dublin.

To add to the consternation of the Belfast Harbour Commissioners, the Port of Dublin has almost completed a two-kilometre tunnel from the city outskirts which will give heavy lorries an exclusive high speed access to cross-channel ferries to England and Wales.

Faced with this and a snarled-up Westlink, the commissioners in Belfast are more than a little edgy.

They are watching customers vote with their wheels and move south.

So they will be at the public hearing to put their case.

Against expansion

Local environment groups will also be there to have their say.

Most do not want to see the expansion of the existing system.

Instead, they just want to see priority given to freight and public transport.

It is unlikely the inquiry will accept such a radical move, but there is increasing sympathy to the problem of too many cars on too little tarmac.

It is no worse than any other large city and better than most.

But the Westlink could rapidly become a total disaster if the problem is not tackled in some way.

So more room will have to be created for cars - if only by moving buses and lorries to their own lane.

Residential areas

There is little prospect for those who live alongside it of it ever getting much better.

But if there were to be extra lanes, there could be some spin-offs.

Already when the system jams up, motorists move to the roads running parallel to the Westlink to bypass the bypass.

This means heavy rush hour traffic using major residential areas as a "rat run" to escape the jams.

A better road system would reduce this traffic, reducing noise, danger and pollution at the same time.

Pollution

So the case for the local community will be a strong one. But not a winner in their terms.

They already face the noise, fumes and delays the Westlink has brought them.

Engineers promise that a faster moving Westlink, even with more traffic, would be quieter and less polluting.

Cynics doubt their case, but it does have more than an element of truth in it.

However, the chances are that once the new improved Westlink opens, its popularity and limited expansion will quickly conspire to bring it to a halt - again.