Business Opinion: The massed ranks of the trade union movement would appear to have won a significant victory at Aer Rianta last week. Despite the Taoiseach's protestation that the Minster for Transport's plan to split the authority into three operating companies is still Government policy, it looks increasingly shaky.

The issue has now been parked until after the coming local and European elections. And even then it will probably remain dormant until the the expected cabinet reshuffle has taken place.

If the idea is quietly abandoned then it will be a big boost for David Begg of ICTU and Jack O'Connor of SIPTU. Arguably the two most high-profile trade unionists in the country they have become personally involved in the Aer Rianta issue, which is seen as having consequences for other state companies, in particular CIÉ.

Mr Begg and Mr O'Connor mounted a very effective campaign over the past few months which saw support for the idea at Cabinet slowly drain away. They honed in on the one argument that the Government would find the hardest to counter: the economic case for breaking up the airports.

The unions challenged the Minister to produce evidence that breaking up Aer Rianta would bring financial benefits and thus underpin the jobs for their members. They demanded - and got - access to financial information, which their own consultants concluded did not prove the case for breaking up Aer Rianta

While it was hard to argue with what Mr Brennan wanted to do at a theoretical level - introduce competition and empower local management - his case was weakened by the lack of any firm evidence that it would work.

This is partly because what he proposed was taking the business into uncharted waters and introducing a range of variables that could not be quantified into some sort of financial model.

The forceful nature of the unions campaign against the break-up of Aer Rianta stands in marked contrast to their apparent indifference to the issue of decentralising the civil service, particularly as the vast majority of their members working in the public and civil service seem to be opposed to it.

As Fine Gael pointed out last week, the Government has not even bothered to make an economic argument for decentralisation. In fact it has simply refused to be drawn on the subject.

There has been no debate in the Dáil, no business case has been presented and no risk assessment carried out, according to Richard Bruton, the Fine Gael finance spokesman.

The reasons for the Government's reluctance to engage on these points are obvious. The costs of decentralisation are going to be massive.

Take for example the Marine Institute, which is in the throes of decentralising to Galway having been evicted from Abbotstown to make way for the now abandoned Bertie Bowl.

A new headquarters for its 140 staff is currently being constructed at Oranmore and it should be finished next year. The budget for its construction is €50 million. This does not include the cost of fitting out the building or the site, which was already owned by the Government, according to the OPW.

If the cost per employee of decentralising the Marine Institute is somewhere north of €350,000, then this suggests something in the region of €3.5 billion for the 10,000 or so who are meant to move under the plan.

And that is just the cost of housing them and does not take into account the millions that will be wasted as a result of the chaos that will ensue when 10,000 civil servants are moved.

Last week the Public Accounts Committee looked at the sorry tale of the provision of accommodation for the probation and social welfare service. An investigation by the Comptroller & Auditor General found that the service had been paying rent on buildings up to three years before signing leases. In addition, fit-out costs estimated to be between €127,00 and €152,000 end up being €1.53 million.

There are numerous other costs that can't be quantified, such as disruption caused by thousands of civil servants swopping jobs either to avoid moving or to move to somewhere they would like to live.

It is quite obvious that as with breaking up Aer Rianta, the economic argument for decentralisation is hard to prove, but the downside is much easier to get a handle on. But for some reason the civil service unions and ICTU are sitting on the sidelines of the debate.

Perhaps, like a great many civil servants, they think the whole thing will just go away once the elections are over.

Another possibility is that they buy into the Government's vision of a decentralised civil service with a true national vision, as against a Dublin-centric agenda. Seems unlikely, given that the Aer Rianta stand-off shows that vision counts for little with SIPTU and ICTU if it runs counter to the desires of their members.

Another, altogether more intriguing, possibility is that according to the the unwritten rules that govern social partnership, victory at Aer Rianta with all its knock on implications for CIÉ and the other State companies comes at a price.

jmcmanus@irish-times.ie