Urbanization in Flanders is at a historical turning point: space is no longer considered an inexhaustible product, but a scarce commodity. Densification thinking is at the heart of this paper.
From static to dynamic
H+N+S's scheme for the Turkish Arnavutköy illustrates how the city is more than a juxtaposition of functions and programs, but also a real metabolism of flows, supply lines and waste movements. In other words, what appears to be a 2D juxtaposition at the top is an intricately interwoven metabolism in 3D; what is invisible in 2D is exposed in 3D. The metabolic view of the city requires a different way of planning. A dynamic planning that cannot be captured in a static 2D plan. 3D planning can provide an interesting answer to this. In other words: 3D planning can only be productive if it helps us to map, unravel and manage these flows. Whereas metabolism of cities is now often graphically captured in two-dimensional flow charts and Sankey diagrams, 3D planning can enable us to capture the management of those flows in all three dimensions. For example, the second figure illustrates how 3D interventions in our urban streetscape generate different airflows and can thereby contribute to improved air quality. But also other flows such as data, transport, water, food and waste cannot be captured with just an X and Y axis. In Flanders only a small number of cities have ventured to explore their metabolism so far. 3D planning offers opportunities to also capture the flows in our cities and actively design them.
From stacking to switching
"Two naked men eating oysters with boxing gloves on": the scene Madelon Vriesendorp depicts of the Downtown Athletic Club in Delirious New York continues to intrigue. In that same book, Rem Koolhaas praised the skyscraper as a utopian device for producing virtually unlimited surface area in metropolitan locations. But Vriesendorp's image shows, above all, the unconventional combinations between all those different programs in the same building and how that can enhance the social interaction of its users. In contrast to current practice, spatial efficiency is more than simply stacking more program in less space. It is about stacking and combining, topping up and complementing, compacting and connecting. If we really want to give the circular economy a chance to develop in the productive city, we will need the three dimensions to accommodate the supply, distribution, processing, use and recycling of our raw materials. The winner of the Europan E16 competition for the Tragel site in Aalst illustrates this nicely with their proposal Reinventing productive heritage. Moreover, this stratification of design and planning unfolds far beyond the ground level and the built heritage. Both on top of and below our cities, space is sought and found in order to realize the housing challenge, energy transition, climate adaptation and inclusiveness. cities such as Helsinki, Amsterdam and Singapore have been working for some time on a sustainable underground space policy. The three-dimensional networks and the public space of connections between these stacked and connected functions can no longer be captured in classical plans and planning. Without ground, no floor plan. Successful 3D planning offers answers not only to stacking, but also to interaction and mutual synergy.
From 2D at once to 4D
These two previous theses show that, although the planning world is attuned to 2 dimensions, in reality people are already designing and building in 3 dimensions. For example, within the discipline of urban design, station environments combine complex property structures with mobility flows and with different public ground levels that seamlessly blend together ; within landscape design, ecoducts and pedestrian bridges interweave biotopes and flows ; within architecture, commercial plinths are combined with housing, community facilities topped with housing, green structures or water roofs. In addition, 3D data is available to governments at various levels, and is being actively used. 3D models of the city are used for hydrological modeling of rivers, and underground sewer systems, sedimentation studies, volume calculations, and so on. The world of planning has few 3D graphic tools yet, but in practice 3D is already everywhere, operationalized through cuts, axonometries, 3D models, BIM, VR and AR.
This raises the question of whether it is really necessary to give a 3D interpretation to 2D environmental planning and we should not set the bar higher. Also, Minister Demir's Policy Note on Environment 2019-2024 explicitly encourages not only multifunctional but also "adaptive use". After all, a shed today can become a classroom tomorrow, underground parking garages transform into water basins or food hubs, roofs become new biotopes or energy production systems. The failure of the regional plan and the integral master planning has forced us to face the facts: a plan without a time dimension, without phasing, without flexibility options or adaptive capacity is doomed to fail. For example, in his recent "Fundamentals of Urban Design," Marcel Smets points out the importance of that fourth dimension. Almost a quarter of the book's concepts deal with the importance of transformation in our contemporary urban design: roadmap, growth trajectory, continuity, change, growth, improvement, memory and renewal. If we want to make 3D planning future proof, it best provides space for uncertainty and adaptivity. Various best practices in master planning such as the plan guide, framework planning or shell approach show us successful alternatives. Functions must be able to change faster than the 3-year lead time for the preparation of an SIP. Societal needs and global influences must be able to be addressed more quickly than only every ten years with a new or revised structure or policy plan. In other words: skip 3D. Go straight for 4D.