On street space, its multifunctionality and urban sustainability

Through this simple approach, it is possible to contribute effectively to the many other purposes and dimensions that the term entails in its three most recognised dimensions: the environmental, the social and the economic. The space of the streets and roads of a city is a resource that allows citizens to circulate and access adjacent buildings. This space also provides air circulation and access to sunlight. Under its surface, it allows the installation of multiple infrastructures essential for the quality of urban life, such as aqueducts, electricity and telecommunication networks. In many cases, it also offers space for vegetation, enriching the city's landscape and biodiversity.

The massification of the automobile has meant that most of the street surface has been destined, almost without exception, and in many cases exclusively, to parking and circulation. Transportation planning and road design have had the automobile as their central axis for more than half a century. Likewise, the geometry of the streets, the material of their surfaces, lighting, and signage are designed for the automobile.

Although there is talk of car-free cities, this purpose, in a generalised way, and the whole of a city, is, in most cases, practically a utopia. Beyond the fact that the car is indispensable in the city, it has become a symbol of status and autonomy and, therefore, an aspirational object for many individuals. Thus, car restrictions, let alone a total ban, are very unpopular measures few politicians would be willing to assume.

But would a more balanced coexistence between cars and the city be possible? An affirmative answer would imply radically rethinking the design of street space, reducing the space allocated to cars to a fairer proportion, and, above all, drastically reducing the speed at which they circulate. In this way, cars could share circulation space with pedestrians and bicycles, reducing the risk of accidents.

The concept of shared space streets is not new. Still, it has not gained the preponderance it should have, and at least in Norway, it is not part of the dominant practice of street design, despite some initiatives such as Gatetuner og miljøgater in Stavanger and other cities. In Norwegian cities, more than two-thirds of streets, particularly those in predominantly residential areas, could be converted to shared surface streets with minimal interventions. In conclusion, the space of the streets, in the era of sustainability and adaptation to climate change, must cease to be the space of the automobile to become a space of multiple functions, such as circulation and access to buildings, space for leisure and gathering of people, and space for biodiversity and climate resilience.

The 10 principles to apply to shared surface streets would be

• Reduce the speed of the car to a maximum of 20km/hour and give priority to pedestrians and bicycles
• Abandoning the geometry of car-centric track design
• Reduce the asphalt surface to strips of minimal sinuous geometry dedicated to shared road mobility for cars and bicycles
• Use permeable surfaces such as cobblestone or stone for parking areas
• Expand the area for vegetation and widely implement bioswales and other natural-based solutions.
• For vegetation covers, preferably use native species or species well adapted to local climatic conditions.
• Use durable, reusable, and low-maintenance materials such as asphalt and stone
• Minimize or avoid paint and other synthetic materials. Those are not very durable, are high maintenance, and generate microplastics and other harmful waste.
• Locate playgrounds and congregants in areas with better sun exposure
• Develop lighting and street furniture in durable materials and prioritise pedestrian comfort