Merging of a lane on a three-lane carriageway
Sign **S-72a** indicates that, on a carriageway with **three lanes in the same direction**, the **left-hand lane** will disappear and its traffic **will merge** into the adjacent lane on the right.

Sign **S-72b** indicates the same, but with the **right-hand lane** merging into the adjacent lane on the left.

In both cases:
- It is only used on **carriageways with three lanes in the same direction**.
- It warns that there will be a **reduction in the number of lanes** on one side.
- It requires vehicles travelling in the lane that disappears to **change lane** in advance and in a safe manner.