A view of the unique table construction above the CAB

In Cartesius, Heddes Bouw & Ontwikkeling is currently constructing Okinawa on behalf of MRP and Ballast Nedam Development. This project will deliver 165 social rental homes for housing corporation Portaal, designed by EVA Architects, alongside 246 private-sector rental homes at the CAB, developed for CBRE Investment Management and designed by Mecanoo.<br><br>Cartesius is shaping up to be a forward-thinking, welcoming urban district inspired by the Blue Zones, where people live longer, healthier, and happier lives together. Designed with health, sustainability, and nature at its core, the neighborhood offers a home that suits both your present and future—a home for life.<br><br>At the heart of Cartesius, the historic CAB is being transformed into The Living Room of the Neighborhood—a vibrant community hub where residents can enjoy shared amenities, healthy food, social gatherings, and spaces for relaxation. With innovative construction methods ensuring a sustainable and future-proof living environment, Cartesius sets a new standard for urban living.

Unique table construction

Richard Sok, project manager, has been involved in the construction of Cartesius from the very beginning. For him and his team, constructing a building is nothing new—but building through an existing historic structure like the CAB presents a unique challenge. Solid engineering is essential to successfully integrating new development within a monument, ensuring both preservation and innovation come together seamlessly.

Unlike a traditional construction site, where work begins at ground level, the CAB occupies that space. To accommodate this, the team is creating a platform beneath the new building, which will serve as the foundation for the apartments above. Richard describes it as building a table—where the supporting columns act as table legs, passing through the existing structure, with a tabletop serving as the base for the new apartments.

Currently, the focus is on installing these critical supporting columns, laying the groundwork for what will soon be a new chapter in the life of the CAB—a historic monument seamlessly integrated into the future of Cartesius.

Prefab

Precast concrete I columns and V columns form the base of the structure and are adjusted with a special anchoring system. "We treat a concrete column like a steel column. But now we set a 15-ton concrete column at an angle to anchors. Without any auxiliary construction involved, we actually just tighten a nut," Richard adds.

At the heart of the CAB redevelopment, precast concrete I-columns and V-columns form the structural foundation, secured with a special anchoring system. “We treat a concrete column like a steel column,” explains project manager Richard Sok. “But instead of additional support structures, we simply set a 15-ton concrete column at an angle, secure it to the anchors, and tighten a nut.” This streamlined process eliminates the need for auxiliary construction, enhancing both efficiency and precision.

Due to the tight constraints of the construction site, columns are delivered just in time, at a pace of six to eight per day, with immediate placement. Storage space is nonexistent, as the crane hook cannot yet reach inside the building, making strategic logistics essential. The installation of all columns is expected to take approximately three months.

While storing concrete columns is not feasible, an innovative solution has been implemented for the HSB (timber frame) elements, which form the façades of the apartments. Instead of outsourcing, the team has transformed the existing CAB hall into a small-scale HSB factory, assembling prefabricated wooden frames on-site.

This approach not only reduces transport emissions but also offers valuable insights into sustainable urban construction. “Typically, HSB elements are factory-made and transported to the site, but by producing them here, we significantly cut down on unnecessary transport,” Richard notes. “Transporting a massive load of raw lumber is far more efficient than moving pre-assembled HSB elements, which contain a lot of empty space.” The findings from this on-site production method will contribute to a research project with Utrecht University of Applied Sciences, aimed at developing more sustainable construction practices for dense urban environments.

Challenge

Every scaffolding structure needed to build the table framework has been engineered down to the millimeter, ensuring a perfect fit within the constraints of the existing monument. The tabletop—essentially the floor of the new building—is first constructed as a temporary platform, fully integrated with insulation, plumbing, drainage, and rainwater systems. Once complete, the temporary work floor is removed, and the existing structure is restored, now transformed into a modernized 2.0 version with a new function.

Building within a historic monument presents unique challenges. “Everything just barely fits,” explains project manager Richard Sok. “Each element requires extra engineering and multiple feasibility checks. We are constructing through an existing building—one that is also a designated monument—so precision is everything.”

By early December, level 0—the tabletop—will be completed. After that, the apartments will be constructed floor by floor using a tunneling method. The new six-story building atop the CAB will feature a sustainable bamboo façade, blending innovation with heritage. Once completed, the CAB will be ready for further development and renovation, preserving its historical character while embracing a future-proof design.

About the CAB

Originally built in the 1930s, the CAB (Central Auto Repair Company) began serving NS (Dutch Railways) in 1949 as a bus and car depot and workshop. During periods when trains could not operate, NS deployed buses from the CAB to maintain service. Decades later, in 2022, this historic site became the stage for yet another mobility milestone—the global premiere of the first bi-directional Hyundai IONIQ 5.

Designed by NS architect Sybold van Ravensteyn, the CAB embodies a rich industrial history. With its robust brick walls, expansive windows, and high ceilings, it reflects the functionality and aesthetic of its time. However, the building’s monumental value extends beyond its architecture—it represents a key chapter in Dutch railway history, marking the evolution from industrial infrastructure to a modern, urban landmark.

As the urban and landscape architect of Cartesius, Mecanoo has reimagined the CAB’s future. The building is set to become the undisputed centerpiece of Cartesius, a vibrant community hub filled with amenities and surrounded by innovative mobility solutions. More than just a landmark, the CAB will be the social and cultural heart of this new urban district.

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