China’s 1,969-foot concrete arch bridge smashes world record with 500-foot span leap

China has set a new benchmark for concrete arch bridges with the Tian’e Longtan Bridge in Guangxi, which now has a 600-meter (1,969-foot) main span. The project won the top prize at Guangxi’s provincial science and technology awards on August 24. This award recognized the engineering that helped concrete arch construction move past limits that had held back similar projects for decades. A 1,460 feet leap The Tian’e Longtan Bridge spans the Hongshui River in Tian’e County, Hechi, within the Guangxi Zhuang Autonomous Region. Its 600-meter (1,969-foot) span beats the previous world record of 445 meters (1,460 feet) for concrete arch bridges. The bridge has two-way, four-lane traffic and is 2,488.55 meters (8,164 feet) long. It opened in 2024 and is now recognized as the world’s longest steel-reinforced concrete arch bridge by span, according to Xinhua News Agency. For decades, engineers in Japan, Croatia, and other major bridge-building countries studied concrete arches with spans approaching 600 meters. However, completed projects in those countries remained below 390 meters (1,280 feet). Cutting the arch’s weight The biggest challenge was the huge weight a long-span concrete arch must support. The report says the bridge’s own dead load makes up over 90 percent of the total stress, and the concrete around the steel framework is more than half of that weight. Engineers changed the arch design to use less concrete. They split the main arch into two ribs and removed parts that carried little stress. This change made the arch narrower, from 23 meters (75 feet) to 13 meters (43 feet). Concrete use dropped from about 40,000 cubic meters (52,300 cubic yards) to 28,000 cubic meters (36,600 cubic yards). The new design used 22 percent less concrete per meter than 400-meter-class bridges, while keeping the same stress level. Tackling concrete cracks The construction team also created new ways to pour the concrete. Controlling cracks is especially important in large concrete arches, since temperature changes and internal stresses can affect the structure as the concrete sets. The resulting technology allowed the project to move beyond an industry limit long associated with concrete arch bridges. Conventional concrete arches were widely considered difficult to extend beyond 400 meters (1,312 feet), while concrete-filled steel tube arches often faced challenges beyond 500 meters (1,640 feet). The Tian’e Longtan Bridge has now reached the 600-meter class, marking a major increase in achievable span length. Lower construction and maintenance costs The bridge also offered an economic advantage over a cable-stayed design. According to stdaily.com, choosing the concrete arch approach saved 110 million yuan ($16.37 million) in construction costs. Over its planned 100-year design life, maintenance costs are expected to be 470 million yuan ($65.9 million) lower than those of the alternative design. During construction in 2023, the International Association for Bridge and Structural Engineering and the Chinese Academy of Engineering hosted a global conference in Nanning, the capital of Guangxi. Experts at the event described the bridge’s technology as “world-class,” according to the report. The project’s latest provincial award now adds further recognition as engineers continue to expand the practical limits of long-span concrete bridge construction.Get the latest in engineering, tech, space & science - delivered daily to your inbox.A versatile writer, Sujita has worked with Mashable Middle East and News Daily 24. When she isn't writing, you can find her glued to the latest web series and movies.