Road narrowing followed by alternating one-way traffic

Sign A warns that the carriageway narrows on both sides. Sign B indicates alternating one-way traffic and requires drivers to give way to vehicles coming from the opposite direction. In the official question, sign B may be found after sign A. This sequence is typical where the road is too narrow for opposing vehicles to pass easily. The first sign warns of the narrowing; a later regulatory sign can determine which direction proceeds and which must wait. Reduce speed at the warning sign and check for any priority signs before entering the narrow section.