Transwijk, Utrecht: new residential towers + basement parking

Woonin is building two residential towers with a total of 215 rental apartments on Lomanlaan in the Transwijk district of Utrecht. The towers will be 14 and 16 storeys high. A fully underground parking garage for cars and bicycles will be created under the houses, and on the ground floor there will be 250 m2 of commercial space available for catering. This will create 17,000 m2 GLA of homes and a parking basement of 3,000 m2 GLA.

The new construction will be realized on the location of the original office buildings and near existing buildings. The soil conditions are such that there are many aquifers and many piles of the original buildings are in the ground. Several studies were carried out for the implementation of the foundation and the choice was made for a CSM wall of 550 mm thickness around the construction pit, a pile foundation consisting of 384 combination piles with a load capacity of 2000 or 3000 kN and a water glass injection, at approximately 12 .0 m – NAP, in order to be able to close the construction pit watertight at the bottom.

The parking garage and basement construction are made of concrete. To support the towers, columns of high concrete quality have been designed on which a beam frame (transitional structure) to the concrete walls of the residential towers is installed.

The client and contractor have expressed the wish to build sustainably. The emphasis is on minimizing dimensions and the concrete mixtures and reinforcement quantities to be used. The coordination of the execution (work sequence and formwork forms), use of different concrete strengths (to reduce the cement content) and limitation of the reinforcement quantities for large spans and loads therefore poses a challenge.

Construction started at the end of April 2024 and will last approximately 3 years.