Clause 33.5 — 33 "Road signs", 5 "Informational and guiding signs", sign 5.5 "One-way road"

"One-way road." Used to indicate a road or a separated carriageway on which vehicle traffic is carried out in only one direction across the entire width.

Clause 1.10 (term "Road")

Road — a strip of land equipped or adapted for the movement of vehicles and pedestrians, or the surface of an artificial structure, including a bridge, overpass, or viaduct, intended for movement.

Clause 1.10 (term "Carriageway")

Carriageway — an element of the road intended for the movement of non-rail vehicles.

Clause 33.4 — 33 "Road signs", 4 "Mandatory signs", sign 4.1 "Straight ahead only" (additionally for differentiation)

"Straight ahead only." Only straight-ahead movement is allowed. The sign does not apply to vehicles operating on established routes. The sign applies to the intersection of carriageways before which it is installed, as well as, if installed at the beginning of the road or after an intersection, to the section of the road up to the nearest intersection. The sign does not prohibit turning right into courtyards or other areas adjacent to the road.

That is, the correct answer is "Sign 4.", considering that according to the definition in the Traffic Rules, it is sign 5.5 "One-way road" that is installed at the beginning of a road or a separated carriageway, along the entire width of which traffic is carried out in only one direction.

The key phrase in the question is: “at the beginning of a road or a separated carriageway, along the entire width of which traffic is allowed only in one direction.” This literally describes the informational sign 5.5 “One-way road” from Section 33 of the Traffic Rules of Ukraine.

To avoid mistakes, it is important to distinguish the one-way traffic sign from signs that only indicate a direction or mode of movement on a specific section. For example, the mandatory sign “Straight ahead” (which is often confused with the one-way sign) only prohibits turns at the nearest intersection or on the section up to the nearest intersection, but it does not mean that the entire road has become one-way. On such a road, oncoming traffic may exist; you are simply required to go straight at that particular spot.

Other similar signs also do not match the wording of the question. A sign indicating the direction by lane regulates permitted maneuvers only for a specific lane or at an intersection, but does not establish one-way traffic along the entire width of the road. The reversible lane sign, on the contrary, means that the direction by lanes can change, so it is not “only one direction” at all times. The dedicated lane sign for route vehicles applies only to the designated lane, not the entire carriageway.

It is specifically sign 5.5 “One-way road” that is placed at the beginning of such a road or separated carriageway so that the driver immediately understands: along the entire width, movement is allowed only in one direction. In the image, it corresponds to option number 4 (it is easy to recognize by the wide arrow indicating the single direction of movement).

Therefore, the correct answer is “Sign 4.”, as it marks the beginning of a one-way road, where traffic moves in only one direction along the entire width of the carriageway.