5 January 2022

Summary of the year at the construction site of the Vistula Spit Crosscut

Two swing bridges were built, which are unique in the country. On the East and West Breakwaters, where concrete XblocPlus blocks are used for the second time in the world, the sheet pile wall driving has been completed. In the lock, which is the heart of the investment, most of the reinforced concrete works were carried out and two gates were installed. This is how 2021 ended at the construction site of the Vistula Spit Crosscut. Works were also carried out, i.a., at the construction of an artificial island, shipping canal, and the building of the Nowy Świat Harbourmaster’s Office. Over 2.8 thousand people were involved in these works.

Thanks to the construction of the Canal on the Vistula Spit, vessels with a draft of up to 4.5 m, length of up to 100 m, and width of up to 20 m will be able to sail from the Bay of Gdańsk to the Vistula Lagoon. The investment started in October 2019 and its first stage will end this year. The investor is the Maritime Office in Gdynia, and the general contractor for the first part of the investment is the NDI/Besix consortium.

“The scope of works includes the construction of a shielding port from the side of the Bay of Gdańsk, a shipping canal with a lock and the construction of closures together with waiting stations from the side of the Bay and the Lagoon, as well as a new road system with swing bridges that will enable passage over the canal in front of and behind the lock, and the construction of an artificial island.” lists Jacek Szymański, Project Director from the NDI/Besix consortium. ”So far, the works have been carried out in accordance with the adopted schedule. We hope that thanks to the favourable weather conditions and the high commitment of all employees, it will still be possible to maintain this pace of work,” emphasizes Jacek Szymański.

How does the construction look like in numbers?

So far, about 98 percent of all sheet pile walls have been driven, i.e. 17.5 km. Also, 96 percent of the scope of earthworks to the level of “0” have been implemented, 59 percent of dredging works in the shipping canal (i.e. almost 574.5 thousand m3), and 52 percent in the area of the fairway (over 413.1 thousand m3). All micropiles were also made.

“More than 519,000 tonnes of stone have already been delivered, which gives 94 percent of the assumed quantity. 97%, that is approx. 9.9 thousand pieces of the XblocPlus precast concrete elements have been produced,” reports Jacek Szymański, Project Director from the NDI/Besix consortium. ”Thanks to them, the amount of concrete on the breakwaters is reduced, the assembly time is shortened and the resistance to climate change increases.”

Let us recall that this type of prefabricated element was first used on the Afsluitdijk dam – the Shield Dam, which is the main dam and dyke in the Netherlands. The Spit Crosscut is therefore the second construction site in Europe and in the world where it is used.

 

Bridges assembled like blocks

The uniqueness of the investment is also evidenced by, among others, the swing bridges – one of the longest structures of this type in Poland.

The swing bridge in Nowakowo, the construction of which has already started as part of the second part of the investment, will consist of spans with a total length of 103 m.

In turn, the total length of one of the two bridges on the Vistula Spit (the first stage) is over 60 m, and the weight of the steel structure of the system with the counterweight is approx. 550-560 tonnes. Each of these bridges consists of 44 components that were manufactured in a steel structure prefabrication plant, brought to the site, and put together like blocks. The heaviest of the individual components weighed over 48 tonnes. Despite such a specific structure and weight, the bridges were assembled with millimetre accuracy and weighted in kilograms. Both the north and south bridges already have use permits. From June last year, the south bridge has been open to traffic, currently drivers use the north bridge.

 

Four gates in the lock

The progress of works is also visible, among others, in the area of the lock and the shipping canal, which are crucial locations for this investment. The lock ensures safe navigation in conditions of changing water levels on both sides of the Vistula Spit.

“Most of the reinforced concrete works have been carried out in the lock. Two gates were installed in the southern pocket. All deliveries for the closures of the northern gates were completed. Works related to the construction of buildings of the southern and northern drive blocks are in progress. In addition, the southern gate is being tested,” says Andrzej Małkiewicz, Head of the Investment Implementation Department at the Maritime Office in Gdynia. u Mierzei Wiślanej

In total, as part of the construction of the lock, four gates will be built that will be used to close it. Each of them is composed of six segments, and each segment of 730 elements. One gate weighs about 160 tonnes, and the heaviest of its elements weights 33.56 tonnes.

 

Million tonnes of sand

It is impressive to see the enormous work carried out on the artificial island built from scratch, which is already visited by numerous birds. In the future, the island is to be their breeding place.

The island has the shape of an ellipse with dimensions of 1906 by 1166 m, a circumference of 4.9 km and a total area of 180 ha.

“The area of steel sheet piling used to shape the island and keep it filled with sand from dredging the bottom of the fairway is almost 112.5 thousand square meters, which means that they would cover almost 16 full-size football pitches,” says Wojciech Czyżewski from NDI. ”One million tonnes of sand will be used to fill the dike, which would fill approx. 37 thousand trucks.”

The total capacity of the island is 9.2 million m3. Approximately 140 thousand tonnes of hydrotechnical stone will be used in its construction, which would fill 3.5 thousand railway carriages.

So far, over 10.5 km of sheet pile walss have been driven there (out of the total number of 10.8 km). The reclamation works inside the cofferdam have also been completed. Works related to the stone riprap are still in progress.

Work on the first part of the construction of the waterway connecting the Vistula Lagoon with the Bay of Gdańsk is to be completed this year, and the entire investment in 2023.

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