This is the world’s longest, highest, pedestrian glass bridge – and it has a deck just 60 centimetres thick. But don’t worry: even though it hangs 300 metres above the Zhangjiajie National Park in the Hunan province of southern China, the 375-metre-long construction is deemed perfectly safe to walk across.
"We drove a 40 ton truck over one of the glass panels, and the deflection was only 2.16 cm,” says Haim Dotan, the Tel Aviv-based architect behind the project. “But this was not enough. So we invited people to take hammers to the bridge, hammering the glass for five minutes. Under these heavy blows only the top layer shattered – the bottom two remained intact.”
The walkway cost 460 million yuan (£48 million) to construct and is made from a triple layer of 50 mm 12m2 glass panes. The bridge itself is built from steel girders filled with reinforced cement, and Dotan says its 2,200 tonne weight helps pedestrians feel at ease: “They feel like they are walking on solid ground.”
Fifty glass balls, each weighing around 500 kg, have been placed on the surface of the bridge to resist vibrations. Two large water reservoirs suspended beneath the span further dampen any movement.
Dotan’s original design called for glass handrails, but simulations showed that windspeed in the valley could reach 56 metres a second, hitting the rails like a sail and destabilising the bridge. Instead, steel poles were used, allowing the wind to pass through; by bending these and the rail atop them, the team found that they could break up the rhythm of groups of people walking on the bridge, helping to prevent the development of resonant vibrations, a phenomenon that troubled London’s Millennium Bridge when it first opened.
After 18 months of construction, the bridge opened in August this year and will allow for sightseeing and, of course, bungie jumping. Work is also underway on a 3,000-seat amphitheatre alongside the bridge, with plans for fashion shows and music concerts to be held on the six-metre span.
The bridge is spectacular to view, but Dotan, designing his first bridge, judges its success differently. “I did not try to design the bridge as a piece of engineering, or architecture, but rather I did anything I could to make the bridge disappear.”
This article was originally published by WIRED UK
