By BBC News Online's Laurence Peter

One of the world's longest bridges will be opened to road and rail traffic on 1 July with the inauguration of the Oresund Link connecting Sweden with Denmark.

The 16 km (10-mile) bridge-tunnel link across the Oresund sound is one of the largest infrastructure projects in European history. It connects the Danish capital Copenhagen to the Swedish port of Malmo.

The Swedish-Danish Oresund Consortium is in charge of the construction, financing, operation and maintenance of the link.

Instead of the one-hour ferry trip, travellers will soon be able to cover the distance in as little as 10 minutes on high-speed trains.

Four lanes will be open to vehicles on the upper deck of the cable-stay bridge, while trains roll across the lower deck.

Cars and trains starting in Malmo will cross over the 7.8 km (4.8 mile) two-level bridge and an artificial island, before diving into an underwater tunnel about 4 km long, which emerges south of Copenhagen, near the city's international airport.

The Oresund Sound has separated the two countries since the last ice age, but now the new link is expected to boost trade and jobs in the region.

Oresund Consortium spokesman Ajs Dam said the project's overall budget of 18.9bn Danish kroner ($2.4bn) was on target.

The bridge has a four-lane motorway and separate rail deck

The consortium expects daily road traffic of 13,000 vehicles on average, with travellers paying a 230 kroner ($29) toll for a one-way crossing.

The loans are scheduled to be paid back within 26 to 27 years, and the bridge is expected to hve a useful life of about 100 years.

The link has four main sections:

• A 430-metre-long artificial peninsula at Kastrup on the Danish coast

• An underwater tunnel about 4 km long connecting the artificial peninsula with the artificial island south of Saltholm

• The 4 km-long artificial island called Peberholm

• A bridge about 7.8 km long

The Oresund Link has one of the world's most advanced automatic monitoring centres.

In the event of a blaze, the fire control system is supposed to swing into action with at the push of a button, Mr Dam told BBC News Online.

Learning from experience

The fires in the Channel Tunnel and Mont Blanc Tunnel were closely studied and appropriate changes were made during the Oresund Link's construction.

"For example, in an emergency the automated system can cut into the signal from national radio broadcasters and reach car radios directly in the tunnel, to alert travellers," Mr Dam said.

It is the world's 10th longest cable-stayed bridge, but Mr Dam said it was by far the strongest.

The decision to build the bridge was taken in 1991, and construction began in 1995.

Engineering challenges

Construction innovations included a purpose-built factory in Copenhagen to produce the tunnel sections, each 20m long. They were then positioned offshore by the world's largest floating crane.

"The engineers say the project has the world's tightest ecological controls for offshore construction," Mr Dam said.

During dredging, no more than 5% of the dredged material was allowed to be spilt into the water, whereas the usual figure can be as much as 13%.

There were just two big setbacks during construction, according to Mr Dam.

The concrete of one bridge pylon section started hardening too soon and had to be cut down.

Then the builders dropped one tunnel section, but it was later recovered from the seabed and lifted into position.