In this situation, are you required to signal your intention to cross this dotted line with the direction-indicator?

In the video you are driving along a residential street where a white van is at the right-hand edge of the roadway, and pedestrians are walking on the pavement on the left; the roadway is divided by a broken line, and on the right, level with the van, there is sign B-21. To go around the van, you have to move onto the left side of the roadway, and you are obliged to signal your intention to cross the broken line. The answer is: yes.

The Road Traffic Act requires a driver to signal an intention to change direction or lane in good time and clearly with the indicator, and to stop signalling immediately after completing the manoeuvre; when changing lanes, the driver must also exercise particular caution. The Regulation on road signs and signals states that a single broken line marks the lanes, and the ban on crossing applies only to solid lines. Moving into the left lane to go around the van is a change of lane - the left indicator warns drivers behind you and those coming from the opposite direction that you are about to be on the left side of the roadway.

Legal basis: Art. 22 para. 1 and 5 of the Road Traffic Act (Prawo o ruchu drogowym); § 86 para. 1 and 3 of the Regulation on road signs and signals