Yeh I thought it was like north/south instead of East and west, but what about switzerland?
And I know about Oceanic airspace, every morning westbound levels normally 300 - 390 (including every 1000ft)
And the same eastbound in the evenings - they don't have to worry about separating opposite direction flights because there's never normally a plane flying east the same time as a westbound, and as the NATs are geared to provide both routes the fastest flight time, (i.e. east bound finding the gulfstream, westbound avoiding it) the tracks never usually cross over any way.