In this situation, when you're changing lanes, are you obliged to use your turn signal?

In the video you enter a dual-carriageway fast road via a slip road; you pass signs A-7 and C-5, and from the acceleration lane, marked with a wide broken line, you must move into the neighbouring lane of the main roadway. When changing lanes, you must switch on your indicator. The answer is: yes.

The Road Traffic Act requires the driver to signal the intention to change direction or lane in good time and clearly, and to stop signalling immediately after completing the manoeuvre; when changing lanes, you give way to a vehicle travelling in the lane you are moving into. The acceleration lane is a traffic lane, so moving from it onto the main roadway is a lane change. You switch on your left indicator while still in the acceleration lane, speed up to the speed of traffic on the roadway, look in the left mirror and over your shoulder, and move into a gap between vehicles.

Legal basis: Art. 22 para. 1, 4 and 5 of the Road Traffic Act (Prawo o ruchu drogowym); § 86 para. 2 point 2 of the Regulation on road signs and signals