Two lanes of a four lane highway are closed and you’re stuck in a traffic jam. If there are no on- or off-ramps, what should you hope to see on the road ahead of you: the other two lanes re-open or one of the two open lanes close?

I think you should hope to see one of the two open lanes close: Since cars are not appearing or disappearing, going from two lanes to one should double the speed of each car, while the reverse will happen when going from two lanes to four lanes.