Dazi Bridge in Daze District, Lhasa

The Dazi Bridge (达孜吊桥) is a suspension bridge located in Dagzê District (达孜区), Lhasa, Tibet Autonomous Region (西藏自治区), China. At the time of its completion in 1984, it was the longest spanning suspension bridge in China, with a main span of 500 meters (1,600 feet). The bridge crosses the Lhasa River (拉萨河) about 30 km (19 miles) east of Lhasa. It played a key role in improving connectivity between the Lhasa city and the Linzhu County (林周县) area.

Bridge Structure and Features

Design and Dimensions

The Dazi Bridge is a steel suspension bridge with a single lane design. The main span is 500 meters, and the bridge deck itself measures 415 meters long and 4.5 meters wide. The bridge is designed to accommodate small vehicles and has a design load of up to 10 tons per vehicle.

  • Bridge Type: Steel suspension bridge

  • Location: Spanning the Lhasa River, downstream from the Lhasa area

  • Main Span: 500 meters

  • Bridge Length: 415 meters

  • Bridge Width: 4.5 meters

  • Vehicle Load: Designed for vehicles weighing up to 10 tons

  • Completion Year: 1984

Construction Features

The Dazi Bridge features 68 main cables with a diameter of 45 mm and is anchored using gravity-based concrete structures. It was built using prestressed concrete and new techniques at the time, addressing challenges in corrosion resistance for steel structures in the high-altitude, harsh conditions of the Tibetan Plateau.

  • Main Cables: 68 cables with a 45 mm diameter

  • Anchor Structure: Gravity-based concrete anchorage

  • Materials Used: Prestressed concrete and steel trusses

Construction History and Innovation

Innovative Techniques

When construction began in 1983, Dazi Bridge was the first major bridge to employ modular pre-fabrication techniques at high altitudes. The bridge was built in segments and required innovative solutions, such as temporary wind cables to mitigate wind-induced vibrations in the canyon area.

Additionally, the use of epoxy coal tar asphalt coating significantly enhanced the corrosion resistance of the steel structure, increasing its lifespan to over 30 years.

  • Construction Start: May 1983

  • Completion Date: December 1984

  • Key Innovations: Use of pre-fabricated sections, temporary anti-wind cables, and epoxy coal tar asphalt for corrosion protection.

Load Testing and Structural Safety

Upon completion in 1984, the bridge underwent rigorous load testing, with structural deformation limited to 82% of the design limit, ensuring its stability and safety. According to 2014 inspections, the bridge’s vibration frequency remains within 0.45–0.68 Hz, confirming its safety during operations.

Traffic and Operational Impact

Daily Traffic and Limitations

As a key junction on National Highway 318 (318国道), the bridge facilitates traffic for small vehicles, with an average daily traffic of about 800 vehicles. However, due to the narrow 4.5-meter width, cargo trucks are unable to use the bridge, requiring a 98-kilometer detour via Najin Mountain Pass (纳金山口), resulting in increased transportation costs for Lhasa city.

  • Daily Traffic Volume: Approximately 800 small vehicles

  • Truck Restrictions: Trucks must detour 98 km around Najin Mountain Pass.

  • Increased Transportation Costs: About 23 million CNY annually for Lhasa city.

Flood Resilience

The Dazi Bridge has stood the test of time, enduring six major flood peaks in the past 30 years. The maximum flood flow reached 2,870 cubic meters per second without compromising the integrity of the bridge.

Replacement and New Developments

The New Dazi Bridge

Given the limitations of the original design, the New Dazi Bridge (新达孜大桥) was built in 2014, located 400 meters downstream from the original bridge. The new bridge was constructed to Class II Highway standards and features a 12-meter-wide main span, designed to accommodate larger vehicles.

  • New Bridge Location: 400 meters downstream of the old bridge

  • Width of New Bridge: 12 meters

  • Construction Start: 2014

  • Completion Date: The new bridge is under construction with higher seismic and traffic load capacities.

Cultural and Historical Significance

The original Dazi Bridge is recognized as a historical structure and has been designated as a cultural heritage site after completing its historic role. It remains an important part of Tibet’s engineering history, showcasing the advancements in bridge construction technology in high-altitude regions.

  • Cultural Status: The old bridge is now preserved as a heritage site.

  • Importance in Bridge Engineering: Represents the breakthrough in bridge construction technology in Tibet.

Visiting the Dazi Bridge

Accessing the Bridge

The Dazi Bridge is located on the Lhasa River, and visitors can reach it by taking a 20-kilometer drive from Lhasa city towards Linzhu County. The area around the bridge is scenic, with stunning views of the river and the surrounding Tibetan Plateau.

  • Distance from Lhasa: 20 kilometers to Dazi Bridge

  • Transport: Self-driving or taking a minibus to Linzhu County

Secret Peach Blossom Valley near Dazi Bridge

Just a short drive from the bridge lies a hidden gem—a peaceful Peach Blossom Valley, known for its tranquil beauty. The area is popular among photographers and nature lovers for its picturesque landscape and the Lhasa River flowing beneath the bridge.

  • Nearby Attraction: Peach Blossom Valley (桃花源)

  • Best for: Photography and nature walks