File: Workers at the site of the National Stadium on September 29, 2007

(BEIJING, November 6) -- For chief engineer Li Jiulin, the National Stadium or the "Bird's Nest," is his beloved child.

From 2003, when the project started, till now, Mr. Li has been staying at the site day and night.

"I've seen it grow up from scratch to design, earthwork, truss hoisting and shape-taking, like a child from birth, learning to walk and being able to run," he told Xinhua.

There were no software formulas, precedents, or experience to be taken as reference. All in all, the engineers found only 10 cross points on an artistic paper to describe the architects' ideas.

The engineers needed to reshape the project's form, set the exact position, direction and angle of every column and steel structure, define the size, height and shape of every space, because all the lines of the draft looked irregular geometrically.

Depending entirely on their own strength and wisdom, the builders developed a kind of brand-new software. Based on the 10 cross points, they conducted repeated calculations and more than 100 experiments to solve the design problems and successfully found the proper model scheme.

To turn the design on paper into reality, Li and his colleagues stuffed the steel tubes with concrete bars, interlinking them with other tubes, thus making longer tubes. They poured concrete into the tubes from underneath to custom-make over 1,300 concrete columns and trusses, which are three times as efficient as those made through foreign methods and saved as much as 37 million yuan (about US$5 million). The columns differ from each other in terms of their inclining angles and none of them is vertical. Li mentioned a column 21 meters in length with a dip of 60 degrees.

Today, the structural elements support each other and converge into a grid formation, just like a bird's nest with interlocking branches and twigs.

With a capacity of 91,000, the venue will host the opening and closing ceremonies, track and field competitions and football finals during the next Olympic Summer Games.