Wildilfe
It is a real problem for smaller wildilfe, but it is a problem not unique to Ireland.
Combined with the proximity of the barrier to the outer lane and the fact that they are continuous for mile after mile, newly opened roads result in carnage for badgers particularly - after a few months there are not nearly as many deaths - because local badger families are mostly killed off by then......Hedgehogs are also seriously impacted and, worse still, otters are also falling victim to these obstructions. Neither otter nor badger populations are strong enough in many areas to sustain such losses. It seem that the roads are bosecting the animals natural territories (as they do many farms) and there is a natural urge on the animals behalf to try to continue to use the traditional routes to/from parts of their territories, only there is a road with juggernauts in the way....
Foxes and deer can tend to navigate over the barriers, IF they get the chance - being disorientated with cars in the outer lane just inches away takes care of a fair few of them too, particularly younger ones.
The original Environmental Impact Studies for our new roads recommended culverts that Otters could use, and regular breaks in the barrier that would allow badgers etc to get through - though these are not ideal as it 'releases' the animal into the outer lane on the other side and thus could have a desavtating effect for a surprised driver. As ever, where there is a will there is a way and an engineering solution (over/underpasses) could be found, but (also "as ever") there is a financial cost that local authorities/NRA/PPP's aren't prepared to meet..........
The Dutch care about their natural environment -
http://www.zwarts.jansma.nl/artefact-499-en.html - here, authorities tend not to give a toss - because it costs to care - will you pay the extra tolls? Maybe when the only badger or otter your kids ever see are roadkills, we will sit up and speak up.
Some stuff
here on biking considerations