Back to merge in turn briefly and to give some context to the discussion and comments made earlier in this thread, I have a couple of points that may be of interest:
* On a high speed road if the traffic flow is high enough then it is lane 2 that will be closed with a chicane leading back to lane 2 when the traffic is in single file if it is lane 1 needing to be closed. This means that the faster moving traffic will filter into the slower traffic which is safer as it's easier for them to find the gap by adjusting their speed and they will have greater visibility as they are looking forwards whereas slower traffic would need to look behind them to move into lane 2.
Lane 1 closures should only start with lane 1 being closed if the traffic count is below a set amount and there is very good visibility to the start of the taper.
* You won't find the queue of traffic in a single lane if it's all moving freely enough for them to be going over 50mph on their approach, the queuing tends to happen when there is a slow approach as was described at the beginning of this post. Merging in turn helps to reduce the tail back of stacking traffic when the cars use both lanes.