In this situation, are you prohibited from overtaking the preceding vehicle on its left?

In the photo you are driving in fog on a roadway with two lanes in your direction; signs D-8 with plates "1000 m" announce the end of the expressway, and ahead of you, in the right lane, there is a car. You are not prohibited from overtaking it on the left. The answer is: no.

The Road Traffic Act states that when overtaking, the driver must pass on the left side of the vehicle being overtaken - this is the basic, permitted form of overtaking, and sign D-8, which tells you that the expressway ends in 1000 m, changes nothing here. Bans on overtaking apply to specific places and situations: the crest of a hill, a bend with warning signs, a junction, a pedestrian crossing, a cycle crossing, a level crossing, sign B-25 - none of them occurs here. However, you must meet the general conditions: have adequate visibility and space, and in fog it is visibility that is the problem - the Act requires you to exercise particular caution in conditions of reduced visibility. So you overtake only when you can see far enough ahead, with your lights on, and if the fog is thick, you give up the manoeuvre even though there is no formal ban.

Legal basis: Art. 24 para. 3 and para. 1 point 1 and Art. 30 para. 1 of the Road Traffic Act (Prawo o ruchu drogowym); § 48 para. 1 and § 50 of the Regulation on road signs and signals