What is the primary objective of implementing a 'Zipper Merge' (Late Dynamic Merge) system in heavy traffic work zones?

1. To encourage drivers to use both lanes up to the merge point and alternate turns.
2. To force drivers to merge into a single lane 2 miles before the taper.
3. To restrict heavy commercial trucks from using left travel lanes.
4. To eliminate all advance warning signs in urban construction corridors during work.