Are you obliged in this situation to make sure that there is no tram approaching?

You are approaching a place where tram tracks cross the roadway - sign A-21 "tram" warns you about this. Before entering the tracks, you are obliged to make sure that no tram is coming, by looking both ways. A tram is heavy, needs a long distance to brake and at such a crossing has right of way over cars.

The basis is the rules on level crossings, which the Road Traffic Act tells you to apply accordingly to tram tracks: a driver exercises particular caution, and before entering the tracks makes sure that no rail vehicle is approaching. A separate rule gives a rail vehicle right of way regardless of the direction it is coming from. If a tram is approaching, you stop before the tracks and let it pass.

Legal basis: Art. 28 para. 1 and 6 and Art. 25 para. 2 and 3 of the Road Traffic Act (Prawo o ruchu drogowym); § 10 para. 3 of the Regulation on road signs and signals