Automobiles: Driving In Ireland

Rules for driving in Ireland - the bit about forcing two lanes where only one is marked is particularly true. At one point on the Kilbarrack Road, there are two arrows painted on the road, side by side. No one I've asked knows if that is to encourage lane-sharing, or just to emphasise the direction of travel. Like the old Dave Allen joke about one yellow line meaning "No parking at all", and two yellow lines meaning "No parking at all, at all". (Maybe it was Jimmy Cricket.)

What does my head in are the new kilometer speed limits. Not the kilometers, themselves. It's the speed limits they've chosen. They obviously wanted nice round numbers. My daily route alternates between 50kph and 60kph. That's 31mph and 37mph. Why not just make it 55kph all the way - 34mph?