Are you allowed in this place to change the lane if you intend to drive straight on?

In the photo you are driving under a flyover in a lane with a lane direction arrow for turning left; the next lane, on the right, leads straight on, and it is separated from your lane by a broken line. If you want to go straight on, you can change to the right lane in this place. The answer is: yes.

The Regulation on road signs and signals states that marking P-1 "single broken line" marks lanes, and crossing it is not prohibited. The Road Traffic Act adds that changing lanes requires particular caution, switching on your indicator early and giving way to vehicles travelling in the lane you are moving into. You change lanes as early as possible, before the line becomes solid.

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