It all started with a dream of building the leading port in Northeast Asia, which called for the construction of a giant bridge.

Early next month, the country's first sea-crossing bridge is expected to open to traffic, which is considered an important step in the development of the Yangshan Deep-water Port.

The Donghai Bridge stretches 32.5 kilometers from coastal Nanhui District to Yangshan Island in the East China Sea, where the deep-water port will be located.

The cable-stayed bridge has taken less than 10 years to build — seven years for a feasibility study, and just 2 1/2 years for actual construction.

While construction was surprisingly quick for a project of its size, workers have discovered that building a massive bridge at sea involves many difficulties — both living and working — that don't affect inland bridges.

Nature was the biggest obstacle.

Typhoons, high winds and tidal waves, which aren't much of a problem inland, can shut down construction for days when working on the sea, engineers working on the project said.

"If the wind power reaches force six in the city, it will reach force eight on the sea — making it difficult to stand, let alone work," said Cui Gejun, an engineer involved in the project.

Zhou Chunwang, a logistic manager working on the project, said construction was halted for weeks in the middle of last year due to a typhoon.

Cui said one of the biggest construction challenges is laying more than 670 girders precisely on pre-constructed piers in weather conditions that could turn over a small ship.

"Our maximum room for error when laying each girder is less than 5 millimeters," he said.

A satellite positioning system was used to ensure the girders were all laid in the correct position, according to Cui.

To help guide the girders into the correct position, they were attached to a special "floating tank" that can lift 2,500 tons and was fastened to the sea bottom by six huge anchors.

Each of the girders took about 10 hours to lay on average, Cui said. They could have been laid much quicker if the bridge was located inland, he added.

Transporting workers and construction materials to the site was another challenge for builders.

Workers had to live at the construction site for months at a time, as it is too far away from other parts of the city for them to commute.

The bridge, which engineers estimate will have a life span of 100 years, will be used to transport cargo to and from the deep water port and as a gateway for tourist heading to the island, which will build up tourism based on its unique geological characteristics.

Dozens of wind-driven generators will be set up along the bridge from 2006 to 2010 to generate green power, according to officials.