Denis Delbaere is a French landscape architect dedicated to teaching and cultivating the development of the “spontaneous green network” along infrastructures. His research focuses on new landscapes—infrascapes—and emphasizes an in-depth, hands-on approach to management practices.

He is an active member of Collectif LIKOTO, working with the urban-sprawling Eurometropolis. He supports the National Research Program on Transport and Energy Infrastructure (ITTECOP) and contributes to the multidisciplinary research and teaching laboratory LACTH (Territory, History, and Materiality). His work is widely published in books and journals.

Over the years, Delbaere has developed a strong focus on landscape architecture critique, which he shares with students and through a publication, banC publiC (publiC benCh). He sees critique as a fundamental pillar of landscape architecture practice and a tool for shaping the evolution of projects.

For his research, Delbaere travels across Europe, studying the overlooked spaces behind infrastructures and how they are shaped.

When you say “new landscapes,” what do you mean?

I believe landscape architecture is driven by the desire to reveal new landscapes. We often assume there are no new landscapes because we think we’ve seen them all. But right now, at this precise moment—when humanity has enclosed the entire world—we are creating new landscapes that remain invisible to us. The ones I focus on are infrascapes, emerging along major infrastructures.

These infrastructures—key instruments of human control over the world—are also where a new kind of landscape is forming, yet we fail to see it. Some people know these places intimately, but they are often those society chooses to overlook: gypsies, various types of dwellers, drug sellers, prostitutes, and others living on the margins. This is what I call a new landscape—a modern counterpart to the medieval saltus.

Before the Industrial Revolution, much of Europe’s territory was structured in concentric layers. At the center was the city. Surrounding it was the hortus, the productive gardens. Beyond that lay the ager, the agricultural fields. Then came the saltus—a collective land open to use by the village. Though often poor soil, unsuitable for farming, it was essential for grazing and connected to the outermost layer, the silva, or forests. Saltus was home to those who couldn’t live within the core: witches, monks, hermits, and many marginalized people. By the 19th century, urbanization and industrial agriculture led to its disappearance.

Today, the environments growing along major infrastructures serve a similar role as the medieval saltus.  That’s the place for a certain kind of nature—not quite forest, not quite garden or farmland. Something in between.

What importance or advantages do infrascapes offer? Can they become corridors instead of barriers, and how do people engage with such infrastructure?

The first thing to consider is that an infrastructure typically uses only 20–30% of its designated surface. Take a highway, for example—the functional part is just the road itself. But the majority of the space is occupied by slopes, verges, embankments, mounds, and similar features. In some cases, this unused infrastructure land already functions as a biological corridor, particularly in suburban areas.

Another key point when thinking about these spaces as a connective, linear, spontaneous green network is that they don’t yet operate in this way. What we observe instead is the organic creation of paths and informal uses driven by the needs of local communities. The main condition for transforming these fragmented spaces into continuous green networks is a shift in maintenance strategies.

We need to rethink how these environments are managed—treating them as multifunctional spaces that provide ecological services, act as biological corridors, serve as public spaces, and even allow for sustainable wood extraction. One solution is to establish linear, parallel paths along the infrastructure, providing better access for maintenance (from behind and not from the road itself) while enhancing the green network. Instead of large-scale clear-cutting, selective small-plot cutting could be implemented, creating diverse ecological habitats. By developing this kind of backbone within infrastructure spaces, both people and wildlife could benefit from improved connectivity and accessibility.

You observe that people use infrastructure environment “that we don’t want to see” as social spaces, I find it puzzling—aren’t these places ugly, loud, and devalued?

I realize my perspective is somewhat marginal, but every time I’ve organized walks along infrastructure, people are surprised. They don’t expect to find such quality in these landscapes. I believe these spaces—these new landscapes—might be the only places in the city where you can have a real landscape experience.

When I walk in the city center, in parks, or even sometimes in forests, I feel like I’m in a kind of theater. The fact that these environments have been deliberately designed for me to find them beautiful is, to me, a problem—you see what I mean.

But when you walk along an infrastructure, you know you’re in reality. You’re seeing the world as it truly is, as it appears to you. And what’s magical in such places is that everything makes sense. There’s a lot of garbage, for example, or abandoned things. And all those things, they become sculptures, ready-mades.

Most people prefer staged aesthetics. But I believe landscape architects shouldn’t focus on cultural aesthetics. Instead, they should work with corporeal aesthetics—something much harder to grasp. Our job is not to create new beauty. Our job is to reveal the beauty that already exists. That’s a completely different approach.

You are currently researching infrastructure while traveling across Europe. What do you observe?

The concept of landscape is closely tied to infrastructure because, in many cases, we need infrastructure to perceive landscapes on a large scale. This idea was explored by Marc Desportes in his book Paysages en mouvement (Landscapes in Movement), where he shows the relation between the evolution of our idea of the landscape and the evolution of mobility.

There are two scales of observation. From the bus—which is how I travel—you can’t see what lies behind the infrastructure. Travelling from city to city, looking at the space behind the infrastructure, I am trying to understand if those spaces are generic. The common idea is that the edges of a highway are the same boring in Portugal and Finland, but this is not the case.

Take Madrid, for example—people there live with highways. This is due to several factors, one being Franco-era urban planning and the transformations of the 1990s, when main streets were converted into highways cutting through the city. But even in suburban areas, highways serve as social spaces. Part of this is cultural, but it’s also because the infrastructure integrates walking and cycling paths and connects to public transport. The way people engage with it completely changes the atmosphere. This contrasts with cities like Lille, Milan, or Ljubljana—each has its own way of using and relating to infrastructure.

When we move beyond the city, these infrastructures function and appear completely differently. What about railway infrastructure?

We can observe the emergence of spread-cities along infrastructure networks. An example is LIKOTO (Lille-Kortrijk-Tournai), a cross-border Eurometropolis that doesn’t follow the classical model of a city with a defined center. It is polycentric, where centres are equally developed. But most people live in an in-between environment—close to the city, yet neither fully rural nor suburban, it’s somewhat a mix of those aspects. This pattern is common across northwestern Europe. In these areas, the functions of spontaneous green networks are not coupled with social spaces or agricultural lands, both of which require restructuring.

Highways can be compared to high-speed rail lines, but there’s a key difference: high-speed rail requires a cleared buffer zone to prevent tree falls, meaning it is usually surrounded by nothing but meadow. In contrast, regional train lines are narrower and more integrated into their surroundings. High-speed rail corridors, however, are almost geological in scale, with dramatic slopes and ridges. These are the landscape monuments we have created over the last few decades.

Beyond infrascape research, you also engage in landscape architecture critique.

I don’t think I would have been interested in the spontaneous green network if I hadn’t been a critic first. Observing how the infrascape is managed—especially all the afforestation—made me think it must be the result of a project, possibly a landscape architecture project. I became curious about how these spaces were designed, what ideas guided them, and how the initial vision compared to the outcome. That led me to the archives of the infrastructure services, where I discovered infrastate—and I was hooked.

To make a valid critique, it is important to look at a project several years after its implementation. Only then can we understand the landscape that has been truly designed—how the plants have developed and how social practices have appropriated and transformed the space. This aspect is almost never documented.

I believe critique should become a central, perhaps the most important, part of a landscape architect’s work. At this moment in time, we must acknowledge that urbanization is over. Of course, it isn’t literally over, but the future lies in reimagining and adapting what has already been built.

Critique allows us to understand both the project as it was conceived and the project as it has evolved—helping us determine what can be done to improve it. Often, with minimal investment, we can work with the natural dynamics of transformation—climate, plants, and animals—to help the project become what it really is.

Perhaps landscape architecture as a profession is now, for the first time, at a stage where we can observe mature contemporary projects and produce a valid critique and design response?

Yes, and critique is not about issuing negative reviews. The goal is to develop the continuity of the projects. In our journal, banC publiC, we believe critique should come from designers rather than social scientists, as designers truly understand what it means to create public space. For us, critique is a way of continuing the project—understanding its evolution and its connection to social and climate changes.

banC publiC publishes critiques that are accessible to everyone, following three key principles:

-We only write about places we have visited in person—this is the foundation of critique.

-We interview at least three people involved at different stages of the project.

-We analyze the drawings, not just the narrative, because the true project is in the sections and plans, not in the storytelling.

In France, we have established an inter-school team across five landscape architecture schools—a network of researchers and teachers exploring how landscape architecture criticism could be taught and we are working to disseminate that in curricula.