Face-lift revitalizes Shanghai's engineering marvel
Lupu Bridge, an engineering marvel and an iconic symbol of Shanghai's greatness, has been revitalized by its first major repair in two decades.
The bridge, known as the world's largest steel arch bridge, underwent the yearlong face-lift to strengthen its foundation and restore its intricate design.
The renovation ensures the bridge's safety for future generations and highlights its significance as an architectural masterpiece, according to the Shanghai Engineering Design Institute, the city's major infrastructure designer.
Constructed on June 28, 2003, the bridge became the sixth bridge spanning Shanghai's Huangpu River.
Its completion has greatly facilitated residents' transportation. It links Pudong and Puxi, and alleviates traffic congestion in the city center.
The bridge transcends its role as a mere transportation link. It represents the spirit of Shanghai, a city constantly reaching for new heights. It also stands as a testament to human ingenuity, blending engineering mastery with artistic allure.
However, over its two decades of carrying heavy traffic with an average of 130,000 vehicles per day in both directions, the bridge experienced defects and damage to its horizontal cables, dehumidification system, interior coating and drainage, the institute said.
Wang Ruilong, the chief designer of the bridge's major renovation, explained that despite the main structure of the bridge having a lifespan of 100 years, the longevity of the auxiliary structures was shorter.
The expansion joints, for instance, have a design lifespan of around 15 years, the cables about 20 years, and the coating lasts from 15 to 20 years, Wang said.
"Therefore, ensuring the bridge's longevity requires both proper construction and maintenance," he told a press briefing on Thursday.
Over the years, the bridge has undergone several maintenance projects, including the overhaul of the horizontal cables in 2016, the road surface in 2017, exterior coating repairs and landscape improvements in 2018, and now, a comprehensive structural repair.
"This major structural repair has reinforced the main structure, replaced aging components of auxiliary facilities, and ensured 100-year lifespan of the bridge," Wang said.
Through this repair, the bridge's structural stability, visual appearance, and intelligent digital features have been further improved, he added.
One significant issue addressed in the repair was the replacement of the vertical supports for the 16 horizontal cables that traverse the bridge deck and structure.
"The horizontal cables are the 'lifelines' of Lupu Bridge, primarily used to balance about 20,000 tons of horizontal thrust transmitted by the bridge's main arch," Wang said.
The original nylon saddles to support the cables had aged, and some even showed cracks.
The renovation has replaced over 1,000 nylon saddles with new supports made with durable new materials to ensure the bridge's stability and reduce safety hazards.
Furthermore, the renovation has optimized the bridge's air supply system and replaced the dehumidification equipment to maintain the humidity of the bridge below 45 percent. Exposure to moisture could affect the bridge's overall safety and quality, Wang explained.
An environmentally friendly water-based coating was also used to protect the bridge's main arch and beam, preventing corrosion.
To provide a comfortable and safe driving experience, the lighting system was also upgraded from the original sodium lamps to energy-efficient LED lights.
It has not only reduced energy consumption by 41 percent but also illuminated the road surface with greater clarity to improve nighttime driving safety.
Moreover, the lighting system can also be better integrated into the city's landscape design, enhancing the urban aesthetics.
Temperature and humidity sensors have been installed across the bridge, along with video cameras to allow real-time monitoring of the bridge's internal condition.
There have been over a dozen cross-river bridges spanning the Huangpu River in Shanghai.
Major renovations were completed earlier on the Nanpu Bridge, known as the first cross-river bridge in the downtown area which opened in 1991, and the neighboring Yangpu Bridge.