Cessna172
I suspect we can agree that there should not be a battle for space. I've generally found that there is less of a battle the earlier one tries to merge. The closer one gets to the obstruction the more reluctant those already in the open lane are to allow another vehicle in front of them.
There cannot be fixed distance from the obstruction at which to merge because it will vary with the volume and speed of the traffic and the number of lanes that are merging. However for the sake of discussion I would suggest that traffic in the obstructed lane should have moved into the open lane a few hundred yards before the obstruction. Any later and we get the battle for space that brings the road to a halt.
Comments suggesting that early merging will result in junction to the rear of the obstruction being blocked are nonsense because by merging earlier rather than later the traffic will continue to flow smoothly.
All this of course relies on car drivers being able to think about other people, what's going on around them and the consequences of their actions and so will never happen.
