Spain has been facing the challenge of congestion in major city access points for years, with persistent traffic jams and elevated pollution levels. To combat this issue, a new traffic sign designated S-51B will gradually be introduced on urban and peri-urban roads, aiming to promote carpooling and optimise mobility in the most congested arteries. This innovation forms part of an update to the General Traffic Regulations pushed forward in 2025, and while it hasn't yet been widely implemented, it's expected to mark a turning point in traffic management across Spanish urban environments.
The S-51B sign represents a substantial change in lane management, giving priority to cars with more than one occupant to reduce the total number of vehicles on the road – something essential for improving traffic flow and air quality. The new sign is easily recognisable by its square design with a blue background, featuring the image of a car with at least two visible people and the "2+" marking accompanied by a forward arrow. This imagery indicates that certain lanes will be reserved exclusively for vehicles carrying a minimum of two occupants, including the driver.
In practice, drivers must be aware of their passenger count before accessing these lanes to avoid improper use and potential fines, which will be equivalent to violations of any other regulatory sign. The rule directly affects how traffic is distributed and establishes a clear incentive for carpooling to access preferential road spaces.
Gradual implementation across Spain
The deployment of this sign won't be simultaneous throughout the country. Its installation will depend on local authorities and the schedule for renewing road signage, beginning with roads that already have High-Occupancy Vehicle (HOV) lanes or at critical points where bottlenecks are common. This approach will allow for gradual implementation tailored to the specific needs of each region or municipality.
Tackling urban congestion
The introduction of the S-51B sign is part of a broader strategy to address urban mobility challenges in Spain. By encouraging vehicle sharing, authorities hope to achieve a significant reduction in the number of cars entering city centres during peak hours, which could lead to measurable improvements in both traffic flow and air quality indices.
Local transport experts predict that these dedicated lanes could reduce journey times for compliant vehicles by up to 15% during rush hours, creating a strong incentive for commuters to coordinate their travel arrangements or utilise carpooling services.