S-51b
High-occupancy vehicle (HOV) lane
Indicates one or more lanes intended exclusively for high-occupancy vehicles. The image shows the number of occupants from which a vehicle counts as high occupancy, as set by the competent road authority in each case. If the lane or lanes are reserved not only for HOVs but also for one or more other specific types of vehicles, the corresponding images may be combined in the same way as on sign S-51a.
Category: Lane signs
Source: General Traffic Regulations (RD 1428/2003), Annex I; designs per the official sign catalog (RD 465/2025)