THE SLOWING economy and shrinking public purse could halt or delay key projects like the €5 billion Dublin metro rail network.

The Government has already signalled that the €180 billion plan to boost the Republic's ailing transport networks, infrastructure and educational facilities will have to be trimmed as resources tighten. The Minister for Finance Brian Lenihan's decision to bring forward the Budget to mid-October has sparked speculation that some of the big projects will not start as early as planned, or will be quietly dumped.

Construction industry sources agree that the expensive and controversial metro urban rail networks proposed for Dublin could be the first to suffer.

They believe the north link, designed to connect with the city's airport, is likely to be delayed indefinitely, while the west route, which will connect up Clondalkin and Tallaght, will not happen.

"Metro north" as it's known will cost an estimated €4 billion to €5 billion, a cost that most experts believe an operator will not recover, so the State itself will have to bear the financial burden.

As a result, it's understood that it is likely to be shelved until the State's finances are in better shape.

Similarly, the Heuston Station-Connolly Station interconnector, which will travel through an existing tunnel that runs under the capital's northside, also looks likely to be delayed. These projects are part of the Transport 21 plan, which the Government unveiled in 2005 and which became part of its subsequent National Development Plan (NDP).

Other features of the plan that might be delayed indefinitely could be various port investment proposals, although it is accepted that many of these are needed.

Mr Lenihan has already said that he has asked Cabinet colleagues to review the elements of the national plan for which their departments are responsible and to pinpoint those projects that should be prioritised.

Earlier this week, the Government revealed that the amount of tax it has collected so far this year is €2.8 billion short of the target set at the beginning of the year, sparking fears of further cutbacks in day-to-day and capital spending.

A Department of Finance spokesman told The Irish Times yesterday that this process is under way.

The Construction Industry Federation (CIF) has already warned that key projects have to go ahead, as much of the infrastructure is needed and it will be too late to begin work when the economy recovers.

As the housing market has slumped and the commercial sector is stagnating, the building industry has taken the brunt of the economic slowdown and the credit crunch, as bank loans are used to fund most construction projects.

The NDP will help keep the industry afloat during the downturn. A key issue for builders bidding for big projects is the Government's decision to introduce fixed-price contracts, which means they have to carry all the associated risks, which in most countries are shared. The CIF is challenging this in the European Court of Justice.

Another concern of the industry group is that if the Government starts rolling back on public-private partnerships, big international players will lose interest in the Irish market.

The Government has a broad commitment to spend 6 per cent of gross domestic product a year on the National Development Plan, but construction industry figures believe that real spending is likely to come in at under 3 per cent.