Fehmarnbelt Fixed Link

The Fehmarn Belt Fixed Link is an immersed tunnel of about 18 kilometres (11 miles) being built under the Baltic Sea between Puttgarden on the German island of Fehmarn and Rødbyhavn on the Danish island of Lolland. Femern A/S, the subsidiary of Sund & Bælt that builds it, describes it as the world's longest immersed tunnel once finished. It will carry a four-lane motorway with continuous hard shoulders in two tubes and two electrified railway tracks in two further tubes, with a fifth tube for technical installations. The map shows the link as drawn from OpenStreetMap, because no official public route layer was found; the German approach to the mainland is drawn, the Danish Rødby-Ringsted line is not.

There is no official opening date. Femern A/S's 2024 annual report called the end-2029 opening significantly challenged, and on 21 January 2026 Femern A/S wrote that opening in 2029 is no longer realistic. Press reports of 16 January 2026 (dpa) derived 2031 from chief executive Mikkel Hemmingsen's remark that the project is two years behind, and a Schleswig-Holstein government page updated on 19 January 2026 also gives 2031; both predate the next statement. On 17 May 2026 Hemmingsen told the newspaper Børsen, as reported by Ritzau, that cars cannot use the link before 2032 at the earliest and that there is no reason to rush the railway until Germany can receive trains; the company's own release the same day says only that the tunnel will open in two stages, road first, with no year. The German transport ministry's project page, dated 7 July 2026, still says 2029. The Danish transport ministry's status report for the first half of 2026 says the lost time is judged unrecoverable and notes that, in the original plan, about 30 months of installations and tests follow 36 months of immersion.

On the German side, DB InfraGO told the federal ministry in July 2025 that the rail connection will be delayed beyond 2029, and the ministry's Infraplan, reported by dpa on 8 October 2026, puts the Fehmarnsund tunnel at 2035 at the latest.

The first 217-metre (712 ft) element was immersed off Lolland on 7 May 2026 and connected to the Danish portal. By 28 September 2026 four of the 89 elements were in place, about 900 metres (2,950 ft) of tunnel; the first special element, about four storeys tall, was next. Femern A/S reported on that date that 16 standard and 3 special elements had been cast. On 30 October 2026 it announced that the structural works on the German portal were complete after about three years.

The treaty makes Denmark solely responsible for financing the tunnel; Germany handles its hinterland connections separately. Femern A/S states that the loans, backed by Danish state guarantees, are to be repaid from motor vehicle tolls and railway charges. Its construction budget is DKK 52.6 billion (about US$7.9 billion) in 2015 prices; the Construction Act framework is DKK 55.1 billion. No new total has been published, but the Danish ministry says an agreement with FLC on an updated immersion programme and the contractor's claims makes the project dearer and lengthens repayment.

The Fehmarn Belt is a gap in the rail and road network between Germany and Scandinavia. Femern A/S notes that the crossing between Puttgarden and Rødby is today made by ferry in 45 minutes, not counting waiting and loading times, and that Hamburg-Copenhagen by train takes about 5 hours. The project is a component of the EU's Scandinavian-Mediterranean (Scan-Med) corridor, which the European Commission describes as running from northern Finland, Sweden and Norway through Denmark, Germany and Austria to southern Italy and by sea to Malta; Femern A/S calls the tunnel a priority project of the Commission.

Femern A/S states that the tunnel will cut the crossing to 7 minutes by train (200 km/h, 124 mph) or 10 minutes by car (110 km/h, 68 mph) and bring Hamburg-Copenhagen by train to about 2.5 hours. The European Commission's corridor page gives the same 2.5-hour figure, with a 2029 completion date that predates the delays described above. Denmark chose an immersed tunnel over other designs in February 2011, according to the German transport ministry's chronology; Arup, a consultant to Femern A/S, says the tunnel was preferred to a cable-stayed bridge for lower navigational risk and lower impact on marine life and bird migration.

The tunnel is an immersed concrete structure of about 18 km (11 mi). Each element holds five tubes: two for the motorway (four lanes, two in each direction, with a continuous hard shoulder), two for an electrified double-track railway designed for a 200 km/h (124 mph) cruising speed, and one for technical installations. The road is designed for a 110 km/h (68 mph) cruising speed. The trench is fully excavated, with an average depth of 12 m (39 ft) and average width of 100 m (328 ft), and the elements sit in it up to 40 m (131 ft) below the sea surface; about 15 million cubic metres (19.6 million cubic yards) of material were excavated.

There are 79 standard elements, each 217 m (712 ft) long and more than 73,500 tonnes (81,000 short tons), and 10 special elements placed about every 2 km (1.2 mi) whose lower level is a basement for the tunnel's electrical installations. A standard element is cast in nine segments of 24 m (79 ft) on one of five production lines at Rødbyhavn, with a sixth line for the special elements. Bulkheads make the element buoyant, the factory basins are flooded like a lock, and the element is floated to the work harbour. Five tugboats tow it to the trench, where IVY, two pontoons each about 105 m by 45 m (344 ft by 148 ft) with 66 winches, lowers it and connects it to the previous element; temporary water chambers in the outer railway tube counterbalance the element's weight imbalance during the lowering (Railway Gazette). The element weight includes about 4,500 tonnes (5,000 short tons) of ballast concrete (Railway Gazette). The element is then secured with gravel and sand backfill and covered with a layer of stone.

Femern A/S gives a crossing time of 7 minutes by train and 10 minutes by car, and a Hamburg-Copenhagen rail journey of about 2.5 hours instead of about 5. The link is user-financed: Femern A/S states that tolls and railway charges will repay the construction loans. Its fact sheet of 28 November 2025 gives a projected repayment period of 36 years; an earlier version of 24 November 2025 and the 2024 annual report cited the 2020 financial analysis with a 28-year period. None of these takes the current delay into account, and the Danish ministry says the FLC agreement lengthens repayment within the period assumed in the Act. The Danish transport minister will set the toll shortly before opening. By 31 December 2025 DKK 29.1 billion (2015 prices) of the DKK 55.1 billion framework had been spent, according to the Danish ministry.

According to Femern A/S's April 2026 fact sheet, around 2,000 people work on the Danish construction site, which covers over 500 hectares (1,236 acres), and about 200 on the German site of about 90 hectares (222 acres). The tunnel element factory and work harbour alone occupy about 220 hectares (544 acres). On 5 October 2026 Sund & Bælt and Odense Port agreed to negotiate exclusively on a partnership for the future use of the production facilities at Rødbyhavn, which Danish law keeps after the elements are made (amendment of 14 December 2023). On the German side, the federal government's answer of 13 February 2026 says Lübeck will not regain a long-distance train connection until the Fehmarnbelt rail link opens.

Dredging the trench produced about 15 million cubic metres (19.6 million cubic yards) of material, most of which is used for land reclamation off Lolland: Femern A/S plans about 300 hectares (741 acres) of nature and recreation areas, and on 2 September 2026 it announced that about 300,000 square metres (74 acres) of new land had opened. Femern A/S counts over 600 hectares of new nature on both sides of the Belt, including 42 hectares of re-established stone reefs near Fehmarn, and says natural areas used on Lolland are compensated at least twice over. It monitors sediment from construction, and in August 2026 described an underwater drone that tracks seabed particles stirred up by the works.

The German plan approval sets strict limits on underwater noise and on where and when work may take place in German waters, which Femern A/S says makes lost time hard to recover. The Federal Administrative Court's rulings of 3 November 2020 and 14 December 2022 on the reef compensation are summarised under Controversies. Femern A/S states that a transformer station on Lolland will supply the tunnel with electricity from the Danish grid.

Environment and the courts. Six lawsuits against the German plan approval reached a ruling on 3 November 2020: the Federal Administrative Court in Leipzig dismissed those brought by two environmental associations, three companies (including the operator of the Puttgarden-Rødby ferry) and the city of Fehmarn. The court found the plan adequately protects biotopes, including reefs, but held that reefs identified only after the approval by a University of Kiel project required a supplementary procedure before work could proceed in that area. On 14 December 2022 the court rejected the complaints against the resulting plan change; Femern A/S says about 9.2 hectares (23 acres) of reef will be destroyed or temporarily damaged, against 25 hectares required by the original approval plus 17.5 hectares added by the change, 42.5 hectares (105 acres) of new stone reef at Sagas Bank in total. Local opposition has largely faded, ZDF reported in July 2026, although the Aktionsbündnis Beltretter had campaigned for years.

Schedule and contractor dispute. Femern A/S's September 2025 explanation lists the late, prototype immersion vessel IVY, parts of the trench found about 30 cm (12 in) deeper than planned, and German plan-approval conditions on underwater noise and sediment spill that were not part of the 2016 contracts. New Civil Engineer reported on 29 January 2026 that FLC's director blamed trench deviations of up to 1.8 m (6 ft) rather than the vessels, while then Danish transport minister Jacob Heinsen called the vessels the biggest risk and questioned whether FLC could finish the job; Femern A/S said such disagreements are not unusual and are handled through contract mechanisms, and the chief executives of Vinci, Aarsleff, Deme and Max Bögl withdrew the director's letter on 10 December 2025. The Danish transport ministry later reported that Femern A/S and FLC had agreed an updated immersion programme covering the contractor's claims, notably on trench quality and the German permit conditions, at a higher cost and a longer repayment period within the period assumed when the Act was passed. Sund & Bælt cancelled the tenders for the rail track and catenary systems and for tolling facilities, reported on 18 February 2026, citing the uncertain schedule.

Cyberattack. A cyberattack hit FLC's IT systems overnight into a Monday in mid-October 2026 (Femern A/S's release of 16 October gives no date). By 16 October work had resumed in several areas, the Rødbyhavn factory was expected to restart shortly, and the Danish National Special Crime Unit was investigating. On 27 October Femern A/S said FLC had told it that data, including personal data, was stolen; Femern A/S said it had no indication that its own systems were affected and referred questions to FLC.

Financing and the ferry operator. Scandlines challenged the Commission's state-aid treatment of the financing; on 28 February 2024 the EU General Court dismissed its challenge and also Denmark's action against the Commission's classification of the funding as state aid. Femern A/S and Sund & Bælt maintain that the link remains a user-financed project.

German hinterland. The German rail connection is the most contested cost. The ministry's project page still shows about EUR 3.5 billion, a forecast the Federal Audit Office dates to July 2020. The federal government's answer of 13 February 2026 gave EUR 5.9 billion for the Hamburg-Lübeck-Puttgarden project, including the road share of the Fehmarnsund tunnel. Minister Patrick Schnieder named EUR 8.1 billion to the budget committee in November 2025, and a confidential Federal Audit Office note for the committee, as reported by the press in June 2026, cites EUR 10.7 billion as of September 2025 and expects the German line to open from 2032/33 at the earliest. A ministry spokesman confirmed a clear cost increase, attributing it to inflation and conditions in the construction sector, without endorsing the figure. For the Fehmarnsund tunnel alone, DEGES now gives EUR 2.306 billion against an original DB estimate of EUR 714 million (dpa, 8 October 2026). Lübeck has no long-distance train service until the rail link opens, according to the federal government's answer; three diverted Intercity trains still served it until 30 April 2026.