How Experimental Solutions Can Catalyse Sustainable Urban Development

In light of the impacts of climate change and evolving socio-economic dynamics in urban areas, there is an urgent need to rethink the design of public spaces—prioritizing more greenery, greater space for active mobility, and enhanced opportunities for social interaction. However, local authorities often face challenges in implementing these changes quickly and flexibly. In a new study by the Franco-German Forum for the Future, we examine the potential of experimental approaches in transforming public spaces.

Rethinking public spaces

City centres in Germany and France are experiencing profound change: the retail sector is evolving, extreme heat and heavy rainfall are becoming more frequent, and larger cars are increasingly taking up space in the city. In the western French town of La Roche-sur-Yon, these challenges were compounded by major construction work in the town centre, which threatened to drive people away. To counteract this, the municipality opted for an experimental redesign of a central shopping street. In collaboration with residents, the city council developed large timber modules that were installed within just nine months. The modules hosted a library, an open-air pub, and an art trail, among other things. Designed to encourage people to linger, the modules are easily adaptable and can be reconfigured for a variety of uses.

Given the often cumbersome nature of urban planning, structurally simple and reversible redesigns of public spaces – such as the example in La Roche-sur-Yon – can inject fresh momentum into urban development. This was a key takeaway from the Franco-German expert dialogue on sustainable urban development, organized by the Franco-German Forum for the Future in cooperation with municipalities, ministries, researchers, and NGOs. The dialogue also highlighted a critical gap: experimental approaches remain rare and need stronger support at both the federal and state levels.

Experimental solutions fast-track change, foster community engagement, and allow for customization

We used the policy proposals emerging from the Franco-German exchange on experimental approaches as an opportunity to take a closer look: Where does the concrete potential for sustainable urban development lie? To explore this, we conducted a cross-case analysis of four experimental initiatives: the redesigned shopping street in La Roche-sur-Yon, the pop-up cycle lanes introduced in Berlin during the pandemic, a public open space project in Munich, and creative road markings in Rouen. These case studies reveal that experimental interventions not only accelerate the transformation of public spaces, they also promote public ownership and enable flexible responses to climate and social challenges. By introducing rapid, temporary changes, such approaches make transformations tangible and invite broader community participation.

Visible temporary structures are also a message to the public: We can quickly adapt the design if problems arise! In La Roche-sur-Yon, for example, one of the modules was redesigned to offer a clearer view of the retail area behind it, demonstrating how practical improvements can be developed step by step during the trial phase. Often, it is only through real-world testing that it becomes clear which designs are effective and accepted by the public. This is where experimental approaches have an edge over traditional urban planning, which is often rigid and “set in stone.” However, for experimental solutions to reach their full potential, they should ideally offer the prospect of permanence rather than being conceived from the outset as short-term interim measures. In Berlin, for instance, most of the pop-up cycle lanes were made permanent within a year by converting them into clearly marked lanes. In La Roche-sur-Yon, following initial, quick adjustments to the wooden modules, the city is now considering a permanent redesign of the shopping street. However, due to budget constraints, this has not yet been secured. In the meantime, the wooden modules remain in place and continue to serve the community.

A cultural shift in public administration

Pursuing experimental solutions also requires a shift in mindset within public administration. As one project manager in Berlin put it, referring to the pop-up cycle paths: “If a space is reorganized using temporary measures, you can observe as a planner that even simple interventions can work well. There’s no need for exhaustive, long-term planning from the outset.” This iterative approach – testing bold, quick solutions that can be refined through real-world experience – is still unfamiliar territory for many administrative bodies. Federal and state governments can play a key role in fostering this cultural shift so that experimentation becomes the norm rather than the exception. One practical example comes from the state of Baden-Württemberg, where the Service Centre for Town Centres supports municipalities by lending pop-up furniture and offering guidance on planning and implementing experimental projects.

Read the full RIFS Study (available in German or French): 

• Experimentelle Stadt, nachhaltige Stadt? Potenziale von Experimentierlösungen im öffentlichen Raum in Deutschland und Frankreich.
• La ville à l’essai? Potentiels des expérimentations pour la transformation sociale et écologique des espaces publics en France et en Allemagne. 

Find out more about the Franco-German Forum for the Future and our recommendations for action at: https://df-zukunftswerk.eu