KORSOR, Denmark -- With a shudder and a roar, two giant tunnel-boring machines are making the first bites in a project that could change the face of Europe.
When it comes to tunnels, most attention has focused on the "Chunnel," the English Channel tunnel between Britain and France. But the Great Belt Link, which will join the two halves of this watery nation, could have a greater long-term impact.
When it is finished in 1996, the Great Belt Link, two bridges and a tunnel, will unite the 2.5 million people in western Denmark with the 2.5 million on the Danish island of Zealand, where Copenhagen sits. Now divided by a 90-minute ferry ride, they will be within a 15-minute drive of each other.
But that is not likely to be the end of it. Denmark and Sweden are expected to agree next spring to the age-old dream of a bridge and tunnel link across the Baltic Sea. And by 2005, Danish engineers hope to build a bridge south to Germany.
The map shows why all this is important.
Denmark is on the northern fringe of Europe. Sweden and the rest of Scandinavia lie across the Baltic, which may be only a fewmiles wide at its southern end but has been enough to create a psychological separation from the rest of the continent. Denmark, for instance, is in the European Community; the other Nordic nations are not.
A Danish-Swedish tunnel-bridge link, from just south of Copenhagen across The Sound to Malmo, Sweden, would tie Sweden to the continent for the first time.
The Danish-German project, called the Fehmarn Belt Link, would be a bridge or a tunnel from Rodby, on the Danish island of Lolland, across the Baltic to the German island of Fehmarn. From Fehmarn, highways run south to Hamburg and the rest of Europe.
What this means is a land link from Lapland to the toe of Italy, with Copenhagen directly astride it. Denmark, now on the fringe of Europe, would suddenly lie in its heart.
Quite a change. Copenhagen, although the capital of Denmark, is almost an economic afterthought. The prosperous Western provinces of Jutland and Fyn do most of their trade with the rest of the European Community, because there's a highway straight south from the Jutland peninsula into Germany.
Barely 5 percent of this trade goes by ferry to Zealand, an insignificant amount for a province that is, after all, in the same country. The Great Belt Link is meant to correct this and tie Denmark together economically.
The Great Belt is the stretch of the Baltic that runs from Zealand to Fyn. About 10 miles wide, it is the channel that most ships use to enter or exit the Baltic.
The Link, which will cost about $3 billion, comes in two parts. The first, just getting started, is the West Bridge, a 4.1-mile combination railway track and four-lane highway, built on 63 legs from Nyborg on Fyn to a tiny island called Sprogo.
From Sprogo, the highway and rail track will split, and the trains will dive into a tunnel that will curve 4.9 miles to Zealand. The railway tunnel is to be finished by 1993; the highway will also be completed except for the paving.
The East Bridge, a 4.2-mile highway between Sprogo and Korsor on Zealand, will be finished in 1996. Because the bridge crosses the deep channel, it will contain a single suspension span 210 feet high and 5,525 feet long -- 1,300 feet longer than the Golden Gate Bridge and the first single span in the world to stretch more than a mile.
Other superlatives apply. A 243-foot-high crane, called the Swan, will float the 6-ton bridge caissons out to sea from the landfill where they are being made. Each caisson will be as big as a 12-story building.
The three years between completion of the two halves of the highway and the railway is deliberate.
Danish Railways is a political power, especially influential in the Social Democratic Party. To get the Socialists' agreement to the Link, planners had to give the railway a three-year monopoly on traffic, which it hopes will persuade travelers to use it even after the highway is opened.
Motorists will save 75 minutes but no money, because the highway toll is to match the present car ferry fare between Nyborg and Korsor, 200 kroner, or $33, each way.
Train passengers will have it cheaper. Train passengers pay $6 for the ferry part of their trip, and that will be added to train fare once the tunnel is finished.
Over the years, Danes have grown used to the leisurely ferry crossing. Six months ago, only 33 percent of them favored the project. That figure is up to 53 percent now and rising. Like Americans, Danes prefer the convenience of their own cars.
But this being Scandinavia, ecologists are out in force.
Special measures have been taken to protect not only herrings and eiders in the Great Belt, but also 2,000 speckled green toads on Sprogo. The only other inhabitant of Sprogo, an eccentric ex-sailor named Kent Lohmann who calls himself the King of Sprogo, has been bought off with a caretaker's job.
The most delicate ecological job has been called "the zero solution."
The difference in salt content in the east and west ends of the Great Belt has created a variety of wildlife that would be upset by a project as big as the bridges. To compensate, engineers have used computer projections to plan new dredging of the channel bottom, changing and shaping it to keep the balance just so.
This stretch of the Baltic is calm, and planners think the bridge will be closed less than two hours every 10 years by high winds. But on a bridge this long, tall vans and house trailers may be banned from time to time.
And although this is a bicycle-riding nation, bikes will be prohibited. Instead, special trucks will ferry bicycles across.