Are you allowed to make a U-turn immediately beyond the informatory sign in this situation?

In the photo you are driving along a road among trees, and on the right there are two signs: at the top B-33 "70", and under it the blue information sign D-3 "one-way road". Immediately beyond this first information sign you are not allowed to make a U-turn - U-turns are prohibited on a one-way road. The answer is: no.

The Road Traffic Act prohibits U-turns in a tunnel, on a bridge, on a flyover (viaduct) or on a one-way road, and also on a motorway and in conditions in which it could endanger road safety; the Regulation on road signs and signals states that sign D-3 means the start or continuation of a road or roadway on which traffic moves in one direction. After a U-turn you would be driving against the traffic, straight at vehicles that do not expect anyone coming from the opposite direction. You may make a U-turn only at a junction where signs do not prohibit it, and if you have to change direction, you do it at the nearest junction or by driving around a block.

Legal basis: Art. 22 para. 6 point 1 of the Road Traffic Act (Prawo o ruchu drogowym); § 44 para. 1 of the Regulation on road signs and signals