Does this sign always oblige the driver to exercise extra caution?

In the picture there is a yellow triangular sign with a fence symbol - A-9 "level crossing with barriers". This sign always obliges the driver to increase attention. The answer is: yes.

The Regulation on road signs and signals states that warning signs warn about places on the road where there is or may be danger, and oblige road users to exercise particular caution; sign A-9 "level crossing with barriers" warns about a level crossing equipped with barriers or half-barriers. According to the Road Traffic Act, particular caution means caution that consists in increasing attention and adjusting behaviour to the conditions and situations changing on the road, to a degree that allows a sufficiently fast reaction - so every warning sign, without exception, requires you to increase attention. With A-9 there is also an obligation from the Act: when approaching the crossing, you exercise particular caution, drive so that you can stop when the barriers start coming down or a red light comes on, and before driving onto the tracks you make sure that nothing is coming. Barriers do not release you from looking - they may be faulty.

Legal basis: § 3 para. 1 and § 6 para. 1 of the Regulation on road signs and signals; Art. 2 point 22 and Art. 28 para. 1 and 2 of the Road Traffic Act (Prawo o ruchu drogowym)