Passing places are a feature of the road system in remote parts of Scotland, such as the Outer Hebrides. They're marked by a white diamond-shaped sign with the words passing place in the middle and, as the name suggests, they're places where a single track road widens enough to make it possible for two cars to pass. The way it usually works is that whichever car comes to the passing place first stops and waits for the other one to drive by. And when it does, it's customary for the drivers to greet each other by raising a hand or making some other gesture of acknowledgement. Their other function is to permit overtaking. If you're chugging along admiring the views and there's somebody sitting on your tail, it's considered polite to pull over into the next passing place and let them overtake you.
We've got passing places galore in North Uist (my adopted island). That is apart from the eight-mile stretch of the new twin track road beween Lochmaddy (main settlement and ferry port) and Clachan (village where the Lochmaddy road meets two other roads, one of them heading up south to the causeway and the island of Benbecula). It's very handy when you have a ferry to catch but somehow without the passing places it just isn't the same.
At the risk of sounding corny, I'd say that single track roads and passing places are not only an integral part of the Hebridean driving experience but also a metaphor for the Hebridean way of life in general: relaxed, friendly and always aware of other people. Naturally, the latter comes with its share of disadvantages as anyone living in a small community will tell you. On the whole, however, I think that instead of miles and miles of motorways, some parts of the mainland could do with more single track roads and passing places.
As they say in Gaelic: Gabh air do shocair.