The Great Belt Fixed Link: Bridges, a Tunnel and Phased Openings

The Great Belt Fixed Link crosses the strait between the Danish islands of Zealand and Funen, using the intervening island of Sprogø as a connecting point. It comprises a road suspension bridge and a railway tunnel on the eastern side and a bridge carrying both road and rail on the western side. The name “Great Belt Bridge” often refers to the most conspicuous structure, the East Bridge, but the 1998 opening to road traffic must be understood within this entire bridge-and-tunnel system.

Earlier bridges had connected Jutland to Funen and linked some islands south of Zealand, yet the Great Belt still separated the eastern and western land-transport networks. Proposals for a crossing existed by the late 1930s, but war prevented them from advancing. The Danish parliament finally decided in 1987 to implement a fixed link, taking the project into construction. It had to serve vehicles crossing the strait while leaving room for ships sailing along it.

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The state-owned Great Belt company, as the client, organized design, construction and operating arrangements. In a 1993 paper, project participant Ole Damgaard Larsen recorded that COWIconsult produced the East Bridge's conceptual design, while tender design was undertaken by the CBR consortium of COWIconsult, B. Højlund Rasmussen, and Rambøll & Hannemann. Dissing & Weitling architects and landscape architect Jørn Westerholt helped coordinate its appearance.

Construction contracts for the East Bridge were signed in October 1991. The Great Belt Contractors (GBC) consortium undertook the substructure, while Italy's CMF Sud was responsible for the steel superstructure. This division of responsibilities shows that the fixed link was not a single work independently completed by one architect: the client, design consortium and contractors handled different systems, and the towers, anchorages and deck had to meet accurately offshore.

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The East Bridge has a main span of 1,624 meters and two side spans of 535 meters each, giving a suspended length of 2,694 meters between the anchorages. It uses a steel box-girder deck and concrete towers 254 meters high. These spans must not be confused with the East Bridge's overall length of about 6.8 kilometers, which also includes the approach viaducts on both sides.

Vertical loads from the suspended deck pass through hangers to the main cables. At the towers, the deck is principally restrained laterally, without the direct vertical support one might ordinarily imagine. The continuous box girder therefore passes through the towers, reducing expansion joints there. Hydraulic buffers between the anchorages and girder limit short-term longitudinal movement while permitting slow expansion and contraction caused by temperature changes.

Gimsing's study notes that these structural arrangements also shape the bridge's appearance. No crossbeam connecting the tower legs is needed beneath the deck, making the relationship between the legs and main cables clearer. The anchorages were also shaped to prevent the offshore structures from appearing overly enclosed and bulky. Structural behavior and architectural expression thus work together.

References: [1]

Some of the link's greatest construction difficulties lay outside the visible East Bridge. A 1998 audit report recalled that an accident on 14 October 1991 flooded two tunnel-boring machines on the Sprogø side. The accident and complex ground conditions led to renegotiation of scheduling and costs. In 1992, the client and contractor agreed on revised completion conditions and allocation of risk.

The railway tunnel and road bridge served different purposes, but delays, interest and contractual changes affected the overall arrangements for the same link. The audit report recorded railway opening in 1997 separately from the planned road opening in 1998. Assessing progress requires distinguishing civil-works completion, system installation, testing and public opening; a continuous bridge deck alone does not establish that the entire link is complete.

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The Great Belt is also a channel for water exchange between the Baltic and North seas. A formal report issued by the Danish Environmental Protection Agency in 2000 stated that the 1987 construction legislation required the project not to alter flow conditions in the strait. Compensatory seabed excavation was therefore used to offset obstruction by the structures, and an international panel of experts subsequently endorsed the “zero-impact” solution for water flow.

This conclusion did not mean that all ecological effects during construction were zero. The report also documented significant effects of sediment disturbance on benthic fauna, mussels, eider ducks and vegetation, with monitoring before, during and after construction. Hydraulic compensation, ecological changes during construction and recovery after completion are three matters requiring separate assessment.

References: [5]

The railway link entered service on 1 June 1997, and the road link opened on 14 June 1998. The combined road-and-rail bridge to the west, railway tunnel to the east and road suspension bridge thus formed a land-transport system across the strait. Road vehicles and trains no longer had to depend on ferry connections across it in the former way.

In his contemporary 1997 article, Nils Francke projected that the rail crossing could fall from about an hour to a few minutes and that the road crossing would also become much faster. These were pre-opening estimates and cannot be treated directly as later measured traffic growth. Financing was likewise connected to use: the company borrowed to build the link and repaid the loans through road tolls and railway payments. The fixed link changed travel conditions while continuing to incur maintenance, operating and debt costs.

References: [1] [3] [4] [5] [6]