Construction entails various activities divided into several phases over a number of years:
The construction sites at Rødbyhavn on Lolland and Puttgarden on the island of Fehmarn were thoroughly prepared in the years prior to the construction phase. This particularly applies to the large construction site on the Danish side.
New channels and access roads have been constructed, utility connections installed and a number of existing buildings at the construction site have been demolished. New water holes and amphibian fences have also been established around the construction site.
Work harbours are under construction at Puttgarden on Fehmarn and at Rødbyhavn on Lolland. Building materials needed for the construction project are sailed out from here, which means that areas in the vicinity of the construction will be protected from vehicles carrying heavy loads.
The work harbour at Rødbyhavn will be by far the largest of the two as this is where production of the tunnel elements takes place. The harbour will also be used for towing the finished tunnel elements into the Fehmarnbelt.
The Danish work harbor was commissioned in July 2022, and the German one exactly one year later.
An 18 km long trench from Denmark to Germany will be dredged to accommodate the tunnel elements. The tunnel elements will be immersed into the trench, joined together and covered with gravel, sand and stone. The surplus material from the dredging will be used to construct new coastal areas near Rødbyhavn and to a limited extent on Fehmarn.
Work on dredging the tunnel trench began in 2021 and is expected to continue until 2024.
A factory will be built east of Rødbyhavn for the manufacture of the 89 concrete elements from which the tunnel will be constructed. Factory halls will accommodate six production lines – five for the tunnel’s standard elements and one for the special elements. Accommodation for the around 1,300 tunnel workers – a 'tunnel village' - is also being built and will provide a good standard of accommodation and catering facilities as well as social activities.
The tunnel village was completed in the spring of 2023. The factory was completed in august 2023.
A portal building will be constructed around the descent into the tunnel on the Danish and German sides. The portal facilities will connect the tunnel railway and motorway with the upgraded and partly newly built roads and railways in the hinterland. The portal will contain a light grid in the tunnel roof to ensure a smooth transition between the natural light and the light in the tunnel.
Work on the portal buildings on the Danish and German sides began in 2022. They are expected to be finished in 2024 on the Danish side and 2025 for the German side.
The tunnel elements will be produced at the factory in Rødbyhavn and towed out to the Fehmarnbelt on an ongoing basis. The contractors will immerse the elements one by one and assemble them from the coast and out towards the middle of the belt from the Danish and German sides.
The first element will be immersed in 2024.
The tunnel tubes will be equipped with the technical installations, which include ventilation, communication facilities, lighting, signage and the motorway and railway installations. Work begins as soon as the first tunnel elements are in position.
All installations in the tunnel will be thoroughly tested prior to the opening. Safety and contingency procedures will also be tested and approved by the authorities before the Fehmarnbelt tunnel opens to traffic.
The Fehmarnbelt tunnel is expected to be completed in 2029.