An important part of the Blankenburg connection is the Maasdeltatunnel, which forms the link between the north and south banks of the Blankenburg connection. The tunnel will be immersed in the river Scheur at a depth of about -30 metres NAP. The immersion of the two tunnel elements is one of the biggest challenges within the project.

Strukton Immersion Projects made the tunnel elements watertight by fitting the four end surfaces of the tunnel elements with bulkheads. The tunnel elements were built in a dry dock close to the construction site in Rozenburg. The tunnel elements have been christened Alara and Isabella. Tunnel element Alara is 205 metres long and tunnel element Isabella is 185 metres long. It is the first time in the Netherlands that tunnel elements of this size have been built and immersed, and that too at a depth of -30 metres NAP.

After fitting all mooring wires and winches, the tunnel elements were carefully checked against checklists. By the end of April 2022, the tunnel elements were ready for transport to the temporary mooring location, Damen Verolme’s 1st working port. On 2 May 2022, the signal was given to fill the construction dock with water during the Go/No-go consultation. On 2 and 3 May 2022, the tunnel elements were transported to the temporary mooring location with precision and craftsmanship.

The tunnel elements remain at the temporary mooring site awaiting immersion.

For an impression, see the video of the raising, unloading and mooring of the elements:

In November and December 2022, Strukton Immersion Projects installed the foundation tiles on behalf of BAAK. These foundation tiles are 7×7 metres and weigh more than 100,000 kilos. They form the temporary foundation for the tunnel elements of the Maas Delta tunnel.

Currently, the ramps on the banks of the Scheur are being completed to ensure that the first tunnel section can be immersed on 31 March.

As many as 12 foundation tiles will be installed for the two tunnel elements, which will be immersed in spring 2023. The foundation tiles weigh about 95 tonnes each and 4 foundation tiles have a size of 7 x 7 metres and 8 foundation tiles have a size of 6 x 6 metres. For placing the concrete foundation tiles, DEME and W. Smit BV, among others, are cooperating. After the foundation tiles are placed, divers will disconnect the lifting equipment at a depth of about 30 metres and then prepare to place the next foundation tile.

Tides and currents at this location make placing the foundation tiles extra challenging, but still manage to place the foundation tiles on the bottom within a few centimetres tolerance. GEOCON is used to determine the position of the tile. For this purpose, the system is duplicated. Both GPS and measuring prisms are used to determine the location and orientation.

SImP has extensive experience in placing the foundation tiles on the ground. Foundation tiles were previously placed by Strukton for the Limerick Tunnel and the North/South Line IJ Tunnel, for example. The gigantic concrete foundation tiles are laid with the accuracy of a few centimetres.

Placing the foundation tiles on the bottom is one of many preparations for sinking the two tunnel elements of the Maasdeltatunnel. The two tunnel elements will be immersed in spring 2023. The Blankenburg connection will make it possible to drive from the A20 near Vlaardingen directly to the A15 in the Botlek.

One special technique that was used is the immersed tunnel technique. This technique has been used for the crossing of the IJ-river under very soft soil conditions and for the crossing of the historic Amsterdam Central Railway Station. The application of the immersed tunnel technique underneath a historic building has never been applied in the world and was a true challenge considering the special immersion trench that had to be created underneath the building. The tunnel was successfully immersed under the Central Station in the summer of 2011. This paper will focus on the technical challenges of the complicated underpass of the historic Central Railway Station and the IJ-river crossing.

This paper will focus on the immersed tunnel part of the link and the particular challenges that the project faced in designing and constructing the  tunnel, these challenges required a significant evaluation in immersed tunnel technology. The tunnel consists of 18 tunnel elements and has a total length of 3.6 km. The tunnel location was characterised by the following conditions:

• a large depth, maximum depth of the tunnel is 48 m below sea level.
• the tunnel is located in a seismic sensitive area.
• the tunnel is founded largely on weak marine clay, but parts also on bedrock.
• part of the tunnel was constructed on a sub sea embankment which is also founded on a weak marine clay.
• the tunnel has been constructed in a location that is facing to the Sea of japan and is exposed to a severe wind and wave environment with large long period swell waves present for part of the year.

Strukton Immersion Projects has taken the initiative from the Working Group 11 (Immersed and Floating Tunnels) of the International Tunneling and Underground Space Association (ITA) to develop a stand together with partners for this exhibition that promotes the immersion of tunnels and caissons. We will be on this stand together with fellow companies that are also closely involved in the Working Group 11.

Strukton Immersion Projects recently floated out the tunnel elements of the Blankenburgverbinding and towed them out of the Keppel/Verolme construction dock. Strukton Immersion Projects will immerse these tunnel elements in March/April 2023. Strukton Immersion Projects is also working on the highway tunnel under the Schelde for the Oosterweelverbinding in Antwerp. This concerns the transport and immersion of 8 tunnel elements.

The magazine E-mosty published an article about the work carried out by Strukton Immersion Projects. The complete five-page article can be found here.

The Maasdeltatunnel forms the link between the north and south banks of the Blankenburgverbinding. Two tunnel elements will be immersed in the river Het Scheur at a depth of 28 meters below sea level. A tunnel with a story, a construction of Dutch Craftsmanship.

The biggest challenge within this project is the immersion of the two tunnel elements, which together form the Maasdeltatunnel.

In a dry dock, a stone’s throw from the construction site in Rozenburg, BAAK built two tunnel elements of approximately 200 meters long, 42 meters wide and 8 meters high. In order to make the tunnel elements watertight, Strukton Immersion Projects provided the four tunnel bulkheads. The modular steel bulkhead panels were placed in the openings with great precision. This precision is crucial because the smallest imperfections can lead to leaks.

After installing all mooring wires and winches, everything was carefully and extensively checked against checklists. A GO during the Go/No Go meeting was the signal to fill the construction dock with water. During the filling process, continuous checks were carried out in the tunnel elements and the tunnel elements were floated up in a controlled manner. With two tugboats the tunnel elements were transported to a temporary mooring location. The floating up and transport was carried out with precision and craftmanship by the team of specialists from Strukton Immersion Projects and DEME Infra.

The tunnel elements will remain at the temporary mooring location awaiting the immersion. In 2024 the final result will be a 924-meter tunnel for traffic between Rozenburg and Vlaardingen.

(Source: among others Rijkswaterstaat, Ballast Nedam, DEME Infra)

SImP will transport the caissons by tugboats from Westpoort to the Ruiterkade behind Central Station, and install the elements with extreme precision on the foundation piles. In this way, the caissons form the framework of the entire bicycle shed. With its years of experience, Strukton Immersion Projects (SImP) is a worldwide specialist in floating, transporting and sinking tunnel elements and caissons.

The floating, transport and mooring of the elements in the Port of Amsterdam took place last week and went smoothly. The final phase for SImP will take place at the end of November and will involve the transport, installation and immersion of the elements on site. For Strukton Immersion Projects, the waters around Amsterdam Central Station are not unfamiliar territory; the company previously carried out the immersion of the metro tunnels for the North/South Line. By making use of its years of experience, the in-house expertise and the cooperation with GEOCON regarding the immersion system, SImP also manages to successfully complete this unique project.

The Oosterweel connection project will be one of the largest infrastructure projects in the Antwerp region, with an impact on liveability and accessibility, and will be carried out until 2030. Lantis is thus initiating the transition to other forms of mobility, which are more sustainable and will lead to better accessibility of Antwerp. One of the projects is the realization of the Scheldt tunnel, the new tunnel under the river Scheldt.

Strukton Immersion Projects signed up for the floating, mooring, immersion preparation and installation of the eight tunnel elements of the Scheldt tunnel. This includes the immersion engineering, preparation and various temporary constructions. Strukton started the engineering immediately. The immersion of the tunnel elements is expected to take place in 2024.

For the construction of the Scheldt tunnel, Strukton is using its extensive specialist knowledge and experience in immersion. Previous similar projects successfully completed by Strukton Immersion Projects include the Busan-Geoje Fixed Link Project in South Korea, the Chioggia Flood Barrier near Venice and the caissons for the foundations of the 1915 Çanakkale Bridge in Turkey, the largest cable-stayed bridge in the world.

The Scheldt tunnel is the most important link in the Oosterweel connection, connecting the left and right banks of the river Scheldt. The tunnel consists of a land tunnel and an immersion tunnel with a total length of 1,800 meters. For this purpose, eight tunnel elements measuring 160x42x10 meters and weighing approximately 60,000 tons will be built in the port of Zeebrugge and then towed to Antwerp via the North Sea and the Western Scheldt.

About TM COTU

TM COTU stands for Tijdelijke Maatschap Combinatie Oosterweeltunnel. The partnership combination consists of the Belgian construction groups BESIX, BAM Contractors, DEME and Jan De Nul. The combination combines the necessary expertise and experience of the participating companies to realize the Scheldt tunnel. TM COTU speaks of the crown jewel of the Oosterweel connection.

Commissioned by municipality of Amsterdam, together with main contractor van Hattum en Blankevoort, Strukton Immersion Projects, takes part in the construction of the IJboulevard project. Strukton Immersion Projects will be responsible for transportation and installation of three concrete caissons, that will form the base of an entirely newly constructed bicycle parking facility. Last year, the engineering has started and within the coming months first building preparations will start. In the beginning of 2022, the concrete base of the bicycle parking facility, that will give room to no less than 4,000 bicycles, will be handed over to van Hattum en Blankevoort.

The number of train and bus passengers will increase significantly in the coming years. Large scale bicycle parking facilities pop up more and more in the larger cities of the Netherlands. Municipality of Amsterdam as well is looking for a solution for parking space for the growing number of bicycles in and around central station. This increasing demand for storage space, has resulted in the commissioning of an large scale underground bicycle parking facility.

The contract was awarded to the main contractor, Van Hattum en Blankevoort, at the end of April. Strukton Immersion Projects had already been in contact with van Hattum en Blankevoort long before and  started working on the tender integrally. Strukton Immersion Projects brings the same technical manager to the project that worked on the Noord/Zuidlijn project. He brings in experience from the earlier project and worked closely with the Port of Amsterdam and the metro timetable.

Special transport

The three concrete caissons will be prepared and built on land at a special location by the end of this year. From that location, during 6 days (24 hours a day), they will be launched in the water. The largest construction measures no less than 90 by 20 metres. The choice to transport by water was not made lightly. This way, both the city and the travellers experience as little inconvenience as possible from the transport. Once the concrete structures have arrived at the IJboulevard, they are installed and joined together, accurate to the millimeter.

Protection for collision

Part of the IJboulevard is a solution for protection against collision of ships that sail on the IJ. Strukton Immersion Projects will deliver this project beginning of 2022. The bicycle storage facility will be ready to be put in use by mid 2023.