Neeltje Jans Radartower

A beacon project in Zeeland

Neeltje Jans, an artificial island in the Oosterschelde, is home to Deltapark, a leisure park showcasing the history and operation of the Delta Works, the greatest engineering feat in Dutch history. Since September 2015, the tiny islet has a new attraction: a fully operational, 115-m radar tower, boasting a record range of 40 km.

Standing guard over the Scheldt

On a mole jutting 1.5 km out into the sea near the Oosterschelde storm surge barrier in Zeeland, the slim silhouette of the Neeltje Jans radar tower is a welcome sight for the many ships using these busy shipping lanes. The tower, the latest addition to the Belgian-Dutch chain of radars in the region, is able to observe and track shipping movements at a distance of up to 40 km.

Rigidity is a must

The concrete tower, which was built with climbing formwork, has a particularly high structural rigidity and ensures a stable radar image, making needle-like Neeltje strong enough to brave the elements for the next 100 years. Excessive wind speeds up to 250 km/h around the head of the tower were measured on a 1/75 scale model during a wind tunnel study. Turbulence would result in a complete shutdown of the radar system and reduce its life expectancy. The radar is consequently positioned in a nonturbulent area, at nine meters above top of roof.

Using a 3D BIM-model, the traditional preliminary design and the final design phase are blended. This allows us to detect and solve design issues at an early stage: a significant added value for a slender construction with important technical installations.

The antenna is the crucial part of a radar system and must remain operational under all environmental conditions. To limit deviations of the radar signals, extremely strict requirements were applied to the design in terms of angular displacement and torsion. That is why we have paid particular attention to the rigidity of this slim tower. Vertical post-tensioned cables equipped this slim tower until mid-height. The concrete mix C53 / 65 is specially designed to ensure an increased modulus of elasticity and a functional design life of 100 years.