Are you obliged in this situation to stop before the traffic light?

In the photo you are approaching a level crossing with half-barriers that are still raised; the traffic lights on both sides of the roadway are showing a flashing red signal, and another car is driving beyond the crossing. You must stop in front of the traffic lights - a flashing red light means no entry. The answer is: yes.

The Regulation on road signs and signals states that a flashing red signal or two alternately flashing red signals mean no entry beyond the traffic lights or other device showing these signals, and that a vehicle stopping because of the signal shown should stop before the stop line, and if there is none - before the traffic lights. The Road Traffic Act requires you to drive at such a speed that you can stop the vehicle in a safe place when a signal given prohibits entry onto the crossing. The red light comes on before the half-barriers start to go down - the train is already close, even though you cannot see it. You do not speed up to "make it", but brake smoothly, stop in front of the traffic lights and wait until the train has passed, the half-barriers have risen and the signal has gone out.

Legal basis: § 98 para. 5 and § 99 para. 1 of the Regulation on road signs and signals; Art. 28 para. 2 of the Road Traffic Act (Prawo o ruchu drogowym)