Ten False Christ Thorns as capstone on reconstruction of Media Square

The Antwerp station district has undergone a true metamorphosis in recent years. Not only did the rear of Antwerp-Central gain an architectural landmark with the new headquarters of DPG Media, but the once so reviled Kievitplein was also given a new identity as a young, dynamic and green Media Square. This will be completed next winter with the planting of ten False Christ thorns.

Antwerp Mediaplein is located in the pedestrian zone at the rear entrance to Antwerp Central Station. It is located on top of an underground parking garage, but is itself, with the exception of emergency and order services, not accessible to motorized traffic. In the middle of the square, a raised area has been laid out in recent months, on which benches and the ten deciduous trees of the Gleditsia triacanthos 'Skyline' type will eventually be placed. 

To provide these trees with the optimal growing conditions, engineering firm Infrabo enlisted the help of TreeBuilders, a GreenMax subsidiary specializing in the design and delivery of the TreeParker tree bunker system on public property.

Tree bunkers

"TreeParker tree bunkers were placed over the entire surface of the square," says Joris De Coster, international consultant at TreeBuilders. "In total, this involves more than 1,500 TreeParkers, which were filled with rich soil. They perform a supporting function and thus not only provide one large, undisturbed rootable space under the pavement, but also prevent the soil from compacting under the influence of daily use. In combination with aeration, watering and tree anchoring, this therefore means that the trees can permanently enjoy soil, water and air. In this case, everything was calculated so that the trees can grow for up to two hundred years."

To avoid damage to the edge of the raised plaza and the paving around it, another Tree Root Guide guide system was placed against the boarding along all sides. 

"These partition walls have guide ribs, which direct the young tree roots perpendicularly downward. Without this special profiling, the roots could circulate along the wall, with a chance of the 'flower pot effect.' And that, in turn, could result in poor tree stability."

Parking as additional complexity

In both the initial study and the final construction of the tree bunkers, the underlying parking garage proved to involve the necessary complexities. 

De Coster: "The trees need water, but at the same time, of course, you have to avoid water from the system entering the concrete structure of the parking lot at all times. Therefore, the entire surface was sealed with a pond liner and a watering system was provided."

Rather unexpected were the level differences on top of the parking lot. 

"The concrete structure was apparently not the same thickness everywhere, with the result that we had to compensate for these fluctuations with our system. If we had originally planned all units to be 80 cm high, it turned out that in some places we only had 70 cm available. Fortunately, because TreeParkers is a modular system whose posts can easily be cut to length or manufactured, we were able to solve this quickly. Thus, one-third of the 1,514 units were eventually shortened to 70 cm, without having to stop or delay the site."