A contractor must install a shifting taper to align traffic across a 12-foot lateral shift on a highway posted at 60 mph. What is the minimum required shifting taper length?

1. 720 feet, which represents the full merging taper length for a 60 mph zone.
2. 540 feet, which represents three-quarters of the full merging taper length.
3. 360 feet, which equals L / 2 (half of the full merging taper length).
4. 240 feet, which equals L / 3 (one-third of the full merging taper length).