Are you merging into traffic when exiting a public road into a car park??

In the video you are driving on a road along a forest towards a large car park on the right, marked with sign D-18 "parking". When you leave a public road to enter a car park, you are not joining traffic (włączanie się do ruchu). The answer is: no.

The Road Traffic Act defines joining traffic as starting to drive after parking or after stopping that was not caused by traffic conditions or traffic rules, and as entering a road from a property, from a roadside facility or its access road, from a road that is not a public road, from a residential area, from a field, from a dirt road onto a paved road, from the shoulder or from a cycle path. So it is always about entering ONTO a road on which there is traffic - a driver who is joining traffic must exercise particular caution and give way to everyone. Leaving the road for a car park is movement in the opposite direction: you are leaving the road, not entering it. This does not mean you can do it carelessly - when turning right, you signal the manoeuvre, move close to the right edge, exercise particular caution and give way to pedestrians and cyclists whose path you cross. You will be joining traffic only when you leave the car park.

Legal basis: Art. 17 para. 1 and 2 and Art. 22 para. 2 point 1 and para. 5 of the Road Traffic Act (Prawo o ruchu drogowym); § 52 para. 1 of the Regulation on road signs and signals