Discover how steel makes it possible to cantilever a glass walkway over a canyon in Tibet and the challenges of getting it there.
Perched on the cliffs of the Nujiang Canyon, with a drop of over 130 metres, Chendu, China-based architecture practice Archermit, has created an awe-inspiring glass walkway with a steel truss structure that follows the course of the river below it. Inspired by the iconic ‘hairpin turn’ road layout of the Nujiang River with 72 turns, the walkway extends outwards with a single cantilever of 37 metres to form a similar ‘hairpin turn.’
The high-altitude glass viewing platform serves as the core structure of the project, explains Zhe Yang, partner at Archermit. “The ground is laid with high-transparency safety glass, creating a true ‘heavenly road’ in the air, transforming the thrilling driving experience of the Nujiang River 72 Turns into an ultimate high-altitude walking experience. This allows visitors to deeply experience the majestic wild beauty and breathtaking allure of the Nujiang Canyon.”
Complimenting and contrasting with the rugged landscape
Yang continues: “The exterior materials primarily consist of weather-resistant steel plates in a Tibetan red colour, responding to the cultural significance of the region’s colours, while also standing out from the surrounding environment. The highly weather-resistant steel is not only sturdy and durable, but its rough texture also engages in a dialogue and fusion with the rugged landscapes around it.”
As Tibet experiences over five months of snow and icy weather each year in most areas and with the construction having to be undertaken at a high altitude with low oxygen levels, building the structure was a challenge, but the reliance on steel as one of the core building materials made the process a little easier.
Steel is well-suited to challenging building conditions
“In Tibet, where transportation is inconvenient and construction is greatly affected by weather conditions, steel structures are an ideal building method due to their minimal on-site construction volume, quick installation and controllable overall costs,” says Yang. “The high-altitude glass viewing platform features a steel truss structure, with the furthest cantilever extending 37 metres and the nearest one extending 27 metres. The truss height near the cantilever support is 2.4 metres, gradually decreasing to 1.5 metres at the cantilever end, which is more than 130 metres above the Nu River.”
The modular nature of the steel structures facilitated the smooth transportation and installation of the viewing platform’s structural materials. “The entire steel truss was fabricated in 46 sections at the factory and then transported to the site for assembly and hoisting, with the main truss of the cantilever portion divided into 26 sections. The hoisting process required extremely high precision, in terms of pre-cambering the cantilever structure, welding and controlling point displacement,” says Yang.
“The high altitude presents a significant physical challenge for construction workers; for example, the Nujiang Viewing Platform is located at an altitude of around 2,800 metres, leading to six different waves of workers just for the pile foundation drilling work. Many workers from lower altitude areas simply cannot adapt to the high-altitude climate, which limits the pool of available labour.”
The high altitude also posed significant challenges for certain construction processes, such as electric welding, concrete pouring and metal sheet installation. “During the project’s construction, we collaborated with multiple authoritative institutions, industry experts, and professors, along with our construction team, to overcome numerous obstacles. After six years of hard work, the project was successfully brought to fruition.”
The effort and endurance have certainly paid off. The Nujiang River 72 Turns Canyon Scenic Area is an incredible feat of design and engineering that looks magnificent from every angle.