In this situation, are you warned of a narrowing on both sides of the road that could impede traffic?

In the video, you are driving in summer on a road through fields, along a row of trees; on the right there is a yellow triangle with the symbol of a roadway narrowing on both sides - sign A-12a "road narrows - on both sides". You are warned of a narrowing on both sides of the roadway which may impede traffic. The answer is: yes.

The Regulation on road signs and signals states that signs A-12a "road narrows - on both sides", A-12b "road narrows - on the right" and A-12c "road narrows - on the left" warn of a narrowing of the roadway on the side shown on the sign, which may impede traffic. On A-12a both edges of the roadway in the symbol come together towards the centre, so the roadway will narrow on both sides. Beyond the sign, the road enters an avenue of trees growing right by the edge of the roadway - there may not be enough room there to pass a wider oncoming vehicle. Warning signs require you to exercise particular caution: you slow down, look to see whether anything is coming from the opposite direction and, if necessary, stop before the narrowing to let the oncoming vehicle through - the Road Traffic Act requires you to keep a safe distance when passing an oncoming vehicle and to stop if necessary.

Legal basis: § 7 para. 3 and § 3 para. 1 of the Regulation on road signs and signals; Art. 23 para. 1 point 1 of the Road Traffic Act (Prawo o ruchu drogowym)