Sixteen times a day the Enterprise express whizzes through the countryside between Dublin and Belfast, a high-quality rail service jointly operated by Iarnrod Eireann and Northern Ireland Railways.
The Enterprise service, introduced last October, may not yet have achieved its original target of linking the two cities in just over 11/2 hours. But it does demonstrate what can be done on a cross-Border basis for an outlay of £90 million, half of it subscribed by the European Union.
An earlier investment of £31 million, again with significant EU aid, linked the Shannon and Erne waterways by restoring the derelict Ballinamore-Ballyconnell canal. This tourism scheme has also had beneficial spin-offs for rural development in a long-neglected corner of Ireland.
And when there was concern about the growing problem of eutrophication (over-enrichment) in the Erne catchment, mainly due to the profligate use by farmers of phosphorus as a fertiliser, the authorities on both sides of the Border set up an early warning system for water pollution.
More recently, consultancy studies of the Erne and Foyle catchments were commissioned with a view to developing joint water-quality management plans. Public consultation was completed just before Easter.
Instead of individual local authorities adopting their own plans, it would make more sense to do this on the basis of river catchment areas, with non-controversial implementation bodies set up for both the Erne and the Foyle, subject to further public consultation.
Waste management is another potential area for North-South co-operation, even if this is merely confined to harmonising regulations on both sides of the Border covering such matters as the recycling of packaging waste and farm plastics, where the North is still somewhat behind the Republic.
Glass collected for recycling in the North comes down to Dublin to be processed by Irish Glass, but high-quality office paper generally travels in the opposite direction to be recycled in Belfast.
"We need to ensure that systems on both sides have the same objectives," said one senior Dublin official.
There is already a lot of consultation between local authorities on both sides of the Border. For example, legislation here requires those in the Republic to send copies of their waste management plans to the adjoining authorities in the North; it is about co-operation rather than setting up institutions.
The idea of establishing a single Environmental Protection Agency for the whole island was floated by Dublin during the tortuous negotiations that led to the Belfast Agreement. Although it would obviously make sense, it may be regarded as somewhat premature at this stage.
Recently agreement in principle was reached on a final route for the Dublin-Belfast motorway between Dundalk and Newry.
Border towns on both sides have benefited from grants from the International Fund for Ireland for civic improvement schemes.
The European Union's Interreg programme, which is specifically targeted at promoting the development of frontier regions in Ireland and elsewhere, has also delivered substantial benefits; the Shannon-Erne waterway was its most high-profile project, but it has also helped to reopen Border roads.
The most glaring absence in the 12 areas of possible North-South co-operation identified in the Belfast Agreement is anything to do with energy. Sources close to the talks say that energy was included in the initial draft, but was later omitted in deference to objections from the Ulster Unionist Party.
However, with Northern Ireland Electricity now openly declaring its intention to build a £150 million power station in the Republic with the aim of undercutting the ESB when the electricity market here is deregulated in 2000, this omission may be academic in the competitive era that lies ahead.