The Blankenburgverbinding (A24) is a new motorway between the A20 and the A15, with a land tunnel under the Aalkeetpolder and a deeper, underwater tunnel under the Scheur. The Blankenburgverbinding joins the A20 and the A15 at an infrastructural node in the shape of a half-star.
BoschSlabbers and Zwarts & Jansma created the design plan for the uppermost fly-over of the intersection with the A15 and the northern portal of the Aalkeettunnel. Currently, we are engaged in the further development of the designs.
The fly-over of the intersection of the A24 and the A15 is part of the larger harbour landscape of the Rotterdam harbour. Our task here is not to hide this industrial landscape, but to showcase what is there.
The look of the node is determined by a hilly landscape with grassy slopes. The groundworks fuse to form a clear spatial gesture. In the triangular space between the A15 and the connecting motorways A15 west and east, an artificial, sculpted grass hill is constructed. High abutments fuse the fly-overs into this hill. Its slopes are sown with flower-rich meadow seeds (Arrhenatherion alliance), suited to the rich clay soil. The fly-overs pierce the hill. The incisions are sharply sculpted, with a grass slope of 1,6 to 1 (i.e. a green soil retaining structure).
At the base of the slope between both motorways, two wadis are created. The shape of these wadis is sharply defined, to fit tightly into the landscaping of the hill. On the fly-over, motorists are offered a spectacular view of Rotterdam harbour and the river.
The northern portal of the Aalkeettunnel is the entry point of the tunnel route, coming from the open peat meadow landscape of Midden Delfland. The aim is to ‘invisibly’ integrate the portal in the landscape, limiting the view from the landscape of both motorway and tunnel structures and preserving structures and elements of the current landscape.
The open tunnel is flanked by broad reedlands and embankments. The Poeldijkse wetering, a local watercourse, is diverted round the Aalkeettunnel, and furnished with a broad reedland zone. This zone integrates the service building and surrounding grounds into the reed zone. The re-creation of the watercourse and the reed zone above the tunnel is made possible by an unconventional design of the tunnel tube construction.
The service building is situated at the head of the tunnel portal. To fit in as close as possible with the dimensions – the granularity – of the existing buildings along the Zuidbuurt, the service building will be subdivided into two compact volumes. A skin of greying lamellas blends the buildings naturally into the rural environment.
Title: Scenic integration Blankenburgtunnel
Location: Maassluis-Rozenburg, Zuid-Holland, NL
Size: 90 ha
Client: BAAK (combinatie Ballast Nedam, DEME Group en Macquarie Capital)
Cooperation: Zwarts Jansma Architecten
Type: DCMF tender and elaboration, integration vision and landscape plan
Image credits: BoschSlabbers, Zwarts Jansma Architecten
Project code: bs-L 16-33