A sponge city building block is to be designed at the Schosshalde cemetery in Bern. This is a traffic development consisting of the car parks, the roadway and the green area. The car parks on the test area will be equipped with grass liner and will be planted with different types of seed to the north and south. The carriageway will consist of permeable asphalt and the tree border will remain a green area without traffic. Rainwater from the surrounding areas will be channelled into the car park area to infiltrate water. This is intended to reduce the amount of runoff and provide the vegetation with sufficient water to fulfil its full ecosystem service potential. To ensure that the trees in the green area have sufficient root space, a buildable substrate is used. This should allow the trees to take root under the car park areas. In order to direct root growth specifically under the built-over area, ‘nutrient lenses’ consisting of charged biochar are built into the substrate. The aim of the project is to scientifically compare two vegetation systems on percolating car parks and quiet traffic areas in urban areas and to gain new insights into root reinforcement in rainwater management systems.