Special Hendriks precon formwork for submersible elements of Maas Delta TunnelSmart formwork solution is decisive

Accessibility to the Rotterdam region is of major economic importance. One of the solutions designed to improve accessibility is the construction of a new motorway, the Blankenburg Connection. It connects the A20 motorway near Vlaardingen with the A15 motorway near Rozenburg. One of the components of this connection is the Maas Delta Tunnel, a submerged tunnel constructed at the bottom of the Scheur River. Hendriks precon supplied the formwork for the construction of the two submersible elements required for this purpose.

Multiple components

The construction of the Blankenburg Connection was awarded to the construction consortium BAAK (Ballast Nedam, DEME and Macquarie Capital). In addition to design and construction, the consortium also assumed responsibility for the tunnel’s financing and its maintenance for a period of 20 years. The route is subdivided into four components. A submerged junction provides the connection to the A20 near Vlaardingen and an elevated junction provides the connection to the A15 near Rozenburg. A land tunnel – the Holland Tunnel – will be built between these two junctions using reinforced underwater concrete. The biggest challenge is the Maas Delta Tunnel, which consists of two submersible tunnel elements that will be submerged at a depth of 27 metres on the bottom of the Scheur River. The elements are 180 and 205 metres long, respectively.

Built in drydock

A striking feature is the location where these tunnel elements are being built: the Damen Verolme Rotterdam drydock to the east of Rozenburg. Where one dock is being used to work on the repair and maintenance of container ships, the submersible elements are being built in the other drydock. They are being constructed in 25-metre sections: first the floor, then the centre walls and finally the outside walls and roof. Once the submersible elements are ready, they will be sailed out as if they were ordinary ships, after which they will be submerged at their place of destination.

Special formwork designed and supplied by Hendriks precon is being used for the outer shell of the submersible elements, consisting of the outer walls and roof. After the floor is poured, the inner walls are constructed using traditional formwork. This way three small tubes are created; one on each side and one in the middle of each submersible element. Two of these tubes will serve as ballast tubes, while the middle tube will be used as a service and emergency escape corridor.

Mobile slab table formwork

The roof of the tunnel deck is constructed using Hendriks precon mobile slab table formwork. Fern van Efferink, Work Planner at BAAK: “Hendriks precon is strong in designing and detailing formwork for unusual applications. The steel formwork we are using here is slim, yet sturdy. The mobile implementation enables us to relocate the formwork easily with a winch. Furthermore, the formwork can be narrowed down somewhat at the top, making relocation as easy as possible.” After relocation, the entire formwork can be lifted mechanically/hydraulically, after which work on the next section can start.