In the UK and France, the +1 was available for use by traffic travelling in either direction. It sounds like in this case, they're talking about one side being allowed to use it for a spell, and then the other. Similar to the overtaking lanes provided here in NZ.

That's a better way. In France it was the closest thing to a state sponsored game of 'chicken' that I've ever seen.

"In the UK and France, the +1 was available for use by traffic travelling in either direction."

I live in the UK, and the only +1 roads I can remember seeing have clear markings showing which side of the road can use the extra lane (never noticed one that included both sides).

In Sweden they are not just marked, but are physically demarcated with a guardrail.

That is an improvement I would like to see here too. My earlier comment was more to address the idea that the current third lane in the UK is some sort of free-for-all, which I don't agree with.

Yeah, almost all the 2+1 roads in the UK have been converted back into two defined carriageways because they were incident magnets.

I can imagine low speed 2+1 roads being OK. It's the 50mph+ ones that lead to horrific crashes - human beings aren't great at negotiating closing speeds of 100+mph.