Well "metric thread" makes some sense so it's kind of still on topic... it just reinterpreted the word thread.
Ireland obviously ignored that international treaty in 1994. I think we maintain that as we drive on the opposite side of the road to the rest of Europe that our roads should look physically different to remind European drivers that they aren't at home anymore!
Our hardshoulders and road edges are all marked out with yellow lines and yellow reflectors.
There are a few other quirks:
The yellow edge reflectors turn to green for 200 meters before all junctions and change to read ahead of sharp bends.
Also, (recent change) all junctions are marked out by a pair of large green reflective plastic posts on either side of the ajoining road.
The NRA (National Roads Authority) are progressively moving everything towards this unique standard.
All warning signs remain the US-style yellow diamonds too and there are absolutely no plans to change to European / UK style triangles.
Ireland had a lot of problems with inconsistant road markings and signage as each county council tended to take their own slightly different interpretations of the national rules. That has changed drastically as there are now Irish standard numbers for each sign and various regulations about how they can be installed. The county councils also had responsibility for most of the main roads in the country removed from them when the NRA was established in the 1990s to manage the national road network and construct the motorway network.
