[Image above] Zhangjiajie Glass Bridge in Zhangjiajie, Hunan, China. It used to be the world’s longest glass bridge when it opened in 2016. Credit: CCTV English, YouTube
When I talk with my college friends about visiting their hometowns in China, they often emphasize the many natural and historical sites that I could tour—the “floating mountains” in Zhangjiajie National Forest Park, the Terracotta Army in Emperor Qin Shi Huang’s Mausoleum Site Museum. Yet there are many recent developments worth visiting in China as well, such as the glass bridges.
As an NBC News article explains, China has undergone a glass bridge building boom in recent years as local authorities seek to entice tourists.
“[State news agency] Xinhua reported that there were at least 60 glass bridges already built or under construction in China by the end of 2016, citing a magazine published by the Geological Museum of China. In 2019, however, state media outlet ECNS estimated that there were as many as 2,300 glass bridges and ‘an undetermined number of glass walkways and slides’ across the country,” the article says.
Some of these glass bridges are known internationally, including
- Zhangjiajie Glass Bridge, the world’s longest glass bridge (430 meters; 1,411 ft) when it opened in 2016.
- It is now the third longest, after the Hongyagu bridge completed in 2018 (488 meters; 1,601 ft) and the Huangchuan Three Gorges bridge completed in 2020 (526 meters; 1,726 ft).
- Coiling Dragon Cliff Skywalk, one of three skywalks located in the Tianmen Mountain Scenic Area by Zhangjiajie City.
- Yellow River 3D Glass Bridge, China’s first 3D glass bridge that allows visitors to enjoy lifelike 3D images on the glass floor from certain angles.
Many people are drawn to visit glass bridges because of the thrill that results from walking on a material known for its brittleness, which can make you feel like it may shatter without warning at any moment. This perception is further enforced when accidents do happen, such as this May when 150-kilometer-per-hour (93-mph) winds blew floor panels out of the Jilin Bridge in the Piyan Mountain Scenic Area and left a tourist stranded for more than 30 minutes.
However, you should not worry excessively about glass bridges shattering. Glass is very strong despite being brittle, and the kinds of glass used in structural applications are manufactured very carefully, a fact that civil engineers regularly emphasize to the public.
“Designers and architects need to think carefully before speccing these materials, but I don’t think people should be worried,” Paul Bingham, a materials scientist at Sheffield Hallam University, says in a NewScientist article.
One factor that receives particular consideration by engineers is the connection between the glass and other structural elements.
“We try and avoid what are called stress concentrations, so we’ll have connections that are padded to allow for some movement. We don’t want to have a rigid connection for the glass because it can precipitate shattering, so the connections with structural glass need to be held [in a way] that allows a little bit of movement at the connection point,” Colin Caprani, senior lecturer in civil engineering at Monash University, says in a Cosmos article.
So although glass itself is rigid, the entire bridge still has movement and flexibility because of its separate pieces, which are often padded with materials like neoprene.
Learn more about designing glass bridges in this Innovate Building Solutions article.
Looking to experience a glass bridge closer to home? This list on Indiatimes.com includes glass bridges in India, Vietnam, France, Canada, and the United States!