With the 2.5 km long “Metro aan Zee” project, a consortium made up of Boskalis Nederland and Swietelsky is realising the conversion and extension of a former railway line into a metro line plus a new stop at the beach of Hoek van Holland. Hünnebeck is supplying the formwork solutions for the various sections of the metro, which are being realised as tunnels, U-sections and elevatedblock sections.
The Dutch coastal town of Hoek van Holland (near Rotterdam) is located at the main estuary of the Rhine and is an important ferry port to the UK. The railway line that used to end at the harbour has already been converted into a metro line and is currently being extended to include a stop right at the beach. 1.5 kilometres of the route under construction runs on a former railway line, while the final kilometre to the beach is being built on concrete foundations and partly elevated on concrete blocks.
The sections of the new metro line also include a 315-metre long tunnel, which was realised using the cut-and-cover method. It was created as a semi-recessed box section (internal height: 5.5 m), which will be covered with sand and laid out as a dune after completion. This is to provide extensive protection for the environment and residents from noise and vibrations. For the production of the box section, Hünnebeck formwork experts developed displaceable tunnel formwork based on the Infra-Kit modular system in combination with H 20 beams.
The main components of the 15-metre long formwork unit were beams and struts from the Infra-Kit L (Light) and M (Medium) load classes, which are especially suitable for light and medium heavy applications in infrastructure construction. Hünnebeck generally offers the double U-beams in lengths between 62.5 and 550 cm (L-version) and 150 to 600 cm (M-version). The modular Infra-Kit system includes struts, spindles, connectors and adapters in order to connect the beams. The advantage of the concept: A few basic components cover a wide range of applications in infrastructure and civil engineering. This includes, for example, the tunnel formwork in this project. Thanks to the user-friendly design, the construction site team was able to quickly assemble the wheeled formwork unit for the first concreting operation and then winch it to the next cycle – 15 times in total.
The already completed tunnel is followed by a 225-metre long, sunken open route along the beach promenade. The semi-submerged, channel-like structure made of in-situ concrete is being constructed by the structural engineers in 15 concreting sections, each 15-metre long, using the robust Manto crane-dependent panel formwork. Thanks to a comprehensive range of panels up to 3.30 metre high, Manto is particularly suitable for rapid shuttering and striking of large wall surfaces.
The final 400 m of the new metro line run directly along the beach. To allow the sand to move freely in strong winds, this section is elevated. The rails will run around 0.5 metre above the ground and have support points made of concrete blocks every 1.5 metre. This final section of the route will certainly be the most interesting part of the journey for future passengers.
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