I drove on a highway like this (in America) this weekend. It's not really shared. It's just that your side will get two lanes for a while, then merge down to on

I drove on a highway like this (in America) this weekend. It's not really shared. It's just that your side will get two lanes for a while, then merge down to one. Then the other side gets two lanes for a while. There are frequently signs saying how far until the next two-lane section, which presumably pacifies impatient drivers.