The severance of animal habitats that will result from Ireland's 700 km roads programme is "potentially much more damaging" to the environment than either the Kildare bypass or the Glen of the Downs road, according to Eugene O'Brien, professor of civil engineering at UCD.

Running roads through animal habitats results in small pockets of land where the animal populations fall below critical mass and die out. O'Brien says it is much less expensive to install tunnels or bridges for animals during the construction stage, rather than later. In many areas there are simple solutions: badgers will travel perfectly happily under the road through concrete pipes just two feet wide and squirrels will cross over the road on rope ladders linking trees on opposite sides," he says.

An EU-sponsored group COST341 was in Dublin recently, drawing up a handbook of best practice. Hans Bekker, a chartered engineer with the Dutch ministry of transport, says it is now normal practice in many parts of Europe to provide "green bridges".

The handbook will not be finished until 2003, so the Irish National Roads Authority has commissioned its own study on the subject. Michael Egan, head of corporate affairs at the NRA, says Ireland is closely following the activities of the European group.

O'Brien says he is providing his civil engineering students with an insight into the impact that roads and railways can have on wildlife and steps that can be taken to minimise the impact.

"Civil engineers are problem-solvers and they will find practical ways of sorting out the problems that arise when wildlife meets transport."