Pingtang Extra-large Bridge on the Pingtang to Luodian Expressway in Guizhou Province

Project Overview:

The Pingtang Super Bridge is a key project on the Pingtang–Luodian Expressway in Guizhou Province. Spanning the Caodu River canyon, the main bridge is a three-tower, double-cable-plane steel-concrete composite beam cable-stayed bridge with a span arrangement of (249.5 + 2×550 + 249.5) meters. The bridge has a total length of 2,135 meters, and the total investment in the project amounts to 1.388 billion yuan. As the largest-span three-tower cable-stayed bridge in mountainous regions, the Pingtang Super Bridge features a central tower that stands 332 meters high, setting a world record for the "tallest concrete bridge tower." Dubbed the "Bridge in the Sky"—the tallest and most beautiful bridge in the world—the Pingtang Super Bridge has become a model for canyon bridges worldwide. The bridge pioneered a groundbreaking construction technique involving the longitudinal movement, rotation, and suspended assembly of entire bridge segments, thereby maximizing the protection of the ecological environment in the bridge area. The accompanying Sky Bridge Service Area has been rated as a national 3A-level tourist attraction and has become a renowned landmark. It has created hundreds of jobs for the local community and has played a vital role in promoting rural revitalization in ethnic minority regions.

Thanks to its innovativeness, high quality, sustainability, harmonious integration with the surrounding environment, and strong public engagement, the Pingtang Super Bridge has successively won numerous prestigious national and international awards, including the Luban Award, the Li Chun Award, the First Prize of the “Bridge Engineering Innovation Award” from the China Highway Society, the Gustav Lindenthal Medal from the International Bridge Conference (IBC), the Global Project Excellence Award from the International Federation of Consulting Engineers (FIDIC), and the Outstanding Infrastructure Award from the International Association for Bridge and Structural Engineering (IABSE). It was also named among Guizhou Province’s Top Ten Scientific and Technological Innovation Achievements for 2022. Construction of the bridge commenced on April 29, 2016, and it was completed and opened to traffic on December 31, 2019. Final acceptance inspection was completed on June 9, 2022.

Project Highlights:

1. Bridge Scale—The Pingtang Supermajor Bridge spans the Caodu River canyon, which is approximately 1,600 meters wide and features a height difference of nearly 600 meters. The elevation of the bridge deck is the primary factor governing the overall scale of the bridge. The terrain on both banks, where the approach sections connect to the bridge, is relatively gentle and at roughly the same elevation. If we were to lower the bridge deck elevation in order to reduce the bridge’s scale, the tunnel lengths required for the approach sections on both sides would increase dramatically, leading to a sharp rise in the overall project cost. Therefore, the final design for the Pingtang Supermajor Bridge adopted a high bridge deck elevation that closely matches the elevation of the approach terraces on both banks.

2. Bridge Design Scheme—In the design of the Pingtang Super Bridge, the elevated terrain in the central part of the valley was fully utilized, resulting in a bridge design featuring a three-tower cable-stayed bridge with main spans of 2 × 550 meters. Compared to a suspension bridge design with 1,300-meter main spans, this scheme achieves cost savings of approximately 100 million yuan and avoids the ecological damage caused by excavation of anchorages on both banks of the suspension bridge. Ultimately, the Pingtang Super Bridge adopts the three-tower cable-stayed bridge design, which offers excellent economic benefits and better harmonizes with the surrounding environment.

3. Elegant Design—The bridge’s location boasts stunning natural scenery: the Caodu River meanders gracefully through mountains, valleys, and fields, while villages along its banks are scattered like stars across the landscape. Inspired by the unique cultural traditions of the local ethnic minorities, the designers incorporated elements such as distinctive costumes and dances into the bridge tower’s architectural design. The tower’s shape emphasizes individual character and places great importance on visual impact, striving to ensure that the tower’s form, scale, and color palette harmoniously blend with the natural environment of the Caodu River canyon. Taking into account the structural requirements of the bridge towers, the designers ultimately settled on a spatial “skirt”-shaped tower design paired with a carefully selected color scheme. The bridge’s overall structure, formed by the seamless integration of towers, girders, and cables, exudes a dynamic vitality, resembling three graceful ethnic minority girls dancing and singing joyfully, welcoming guests from all directions.

4. Outstanding Structural Design—The Pingtang Super Bridge adopts a cable-stayed bridge design featuring three towers and double-cable planes made of steel-concrete composite girders. The three elegantly “skirt-like” tower structures are strategically arranged along the canyon’s contours, with the central tower setting a world record for the tallest concrete bridge tower. Together, they form a world-class bridge that seamlessly combines strength and aesthetic appeal. To enhance the stiffness of the towers and ensure overall structural compatibility across the entire bridge: ① The conventional plate-type tower structure was transformed from bending-dominated loading into an axial-force-bearing configuration based on a spatial mega-truss system; ② A structural system was proposed featuring “hinged connections between the central tower and the beam, with vertical supports at the side towers,” accompanied by the development of ultra-high-capacity multi-directional spherical steel bearings capable of accommodating complex rotations and novel viscous dampers; ③ The central tower incorporates detailed structural features distinct from those of the side towers (the central tower’s column spacing along the bridge axis is 20 meters, with a width of 5 meters and a wall thickness of 1.5 meters, whereas the side towers’ column spacing along the bridge axis is 15 meters, with a width of 4.8 meters and a wall thickness of 1.2 meters). This innovative approach effectively addresses the challenge of achieving structural stiffness compatibility in ultra-high piers and multi-tower cable-stayed bridges. The main girder adopts an I-shaped steel-concrete composite section composed of a steel main girder, steel cross beams, and a concrete deck slab. The cable-stayed system features a spatial double-cable-plane arrangement with a dense, fan-shaped cable layout; each tower is equipped with 22 pairs of cables on one side, using low-relaxation, galvanized-aluminum alloy high-strength parallel wire cables.

5. Overall Construction Plan for the Main Girders—The transportation conditions at the bridge site are challenging, and the construction site is narrow and steep. During the construction of the Pingtang Super Bridge, the design team and all participating construction units collaborated sincerely and worked closely together, pioneering the “steel-girder full-segment longitudinal shifting and rotational lifting assembly technique.” This technology effectively ensured the structural integrity of the girder segments during erection; significantly reduced the construction footprint beneath the bridge, thereby maximizing the protection of the ecological environment in the bridge area; greatly decreased the amount of high-altitude cantilevered assembly work on the steel girders, effectively enhancing construction safety, substantially improving assembly efficiency and quality, and opening up a new chapter in the industrialized construction of bridges in mountainous regions. The technology has been successfully applied and promoted to several projects, including the Yunwu Bridge in Guizhou (a cable-stayed bridge with a main span of 480 meters) and the Jiang’an Yangtze River Second Bridge in Sichuan (a three-tower cable-stayed bridge with main spans of 2 × 400 meters). The technology boasts broad prospects for further application and demonstrates significant socio-economic and ecological benefits.

6. A New Approach to Bridge-Tourism Integration—The design incorporates a novel concept of bridge-tourism integration, seamlessly coordinating the design of the grand bridge with the service areas at its approach spans. As a result, China’s first mountainous bridge-tourism integrated highway service area—the “Sky Bridge” Service Area—has been built. This service area closely integrates various functions, including transportation, sightseeing, tourism, and accommodation. Leveraging the unique scenery of the Pingtang Super Bridge and the Caodu River Canyon, it achieves a perfect harmony among people, bridges, and the natural environment. The Sky Bridge Service Area has successively earned titles such as “Guizhou Provincial Science Education Base,” “National Highway Science Education Base,” and “National Highway Tourism Specialty Service Area.” It has also been rated as a National 3A-level Tourist Attraction and has become a well-known landmark. Since its opening, it has welcomed over 2 million visitors, generating total consumption exceeding 10 million yuan. In 2022 alone, it hosted more than 3,000 students participating in study tours, yielding research and education revenue of over 600,000 yuan. While providing high-quality travel services to passing travelers, the Sky Bridge Service Area has also created hundreds of local jobs, thereby boosting rural revitalization in ethnic minority regions.

Honored Achievements:

Second Prize for Scientific and Technological Progress of Guizhou Province
International Bridge Conference IBC “Gustav Lindenthal” Award
FIDIC Global Project Excellence Award of the International Federation of Consulting Engineers
IABSE Global Outstanding “Infrastructure Award” from the International Association for Bridge and Structural Engineering
China Construction Engineering Luban Award (National High-Quality Project)
High-Quality Highway Transportation Engineering Award (Li Chun Award)
Top Ten Scientific and Technological Innovation Achievements of Guizhou Province in 2022
First Prize, China Highway Society Bridge Engineering Innovation Award
First Prize, Guizhou Province Outstanding Engineering Survey and Design Award
We have obtained 6 invention patents, 21 utility model patents, 1 design patent, 8 software copyrights, 10 construction methods, and 1 monograph. We have also published 55 papers in core journals or higher (including 5 SCI papers and 10 EI papers).