[vacri]

Here in Australia, 2+1 roads aren't very long - they're usually just long enough for a few cars to overtake a slowpoke, then a few kilometers further on you'll get another chance. You can't really cruise double-abreast on these roads, as they're not long enough for that.

Similarly you can't really bottleneck because the only input is a single-lane road - they're not long enough to add anything more than trivial traffic in rural areas.