Which of the following vehicles may enter the road once you go past this sign?

In the photo, before the entrance to a narrow, tree-lined avenue, there is sign B-3 "no entry for power-driven vehicles, except single-track motorcycles" (red border, outline of a car). Only a single-track motorcycle may enter the road beyond this sign - answer A.

The Regulation on road signs and signals states that sign B-3 means a ban on the movement of power-driven vehicles, and the ban does not apply to single-track motorcycles. The exception is narrow: it covers only motorcycles on two wheels. A three-wheeled motorcycle with symmetrically placed wheels is also a motorcycle under the Road Traffic Act, but not a single-track one - the ban covers it. A light quadricycle is a motor vehicle, and therefore a power-driven vehicle, and it is not a motorcycle - it cannot enter either. The sign does not apply at all to bicycles and other vehicles without an engine, because they are not power-driven vehicles. The purpose of the sign: only vehicles that take up little space and do not damage the surface are let into the narrow avenue, and they do not take space away from pedestrians and cyclists.

Legal basis: § 18 para. 1 of the Regulation on road signs and signals; Art. 2 point 32, 33, 42c and 45 of the Road Traffic Act (Prawo o ruchu drogowym)