With a total floor area of 4,030 square meters and weight of approximately 7,500 metric tons, a traditional shikumen-style building complex is being relocated for better protection in Shanghai, with the help of 432 small robots.

As China's largest group relocation project of its kind, the Huayanli complex located within Zhangyuan in Shanghai's Jing'an district has been moving approximately at an average pace of 10 meters per day since May 19 using 432 small walking robots, according to Shanghai Construction No 2 (Group) Co Ltd which is in charge of construction. It is scheduled to return to its original location by Saturday.

Built between the 1920s and 1930s, the Huayanli complex comprises three brick-and-wood structures. The temporary relocation was initiated to enable the construction of a three-story underground space beneath Zhangyuan, which stands as one of Shanghai's largest and best-preserved shikumen complexes with a history exceeding 140 years.

The underground development, covering over 53,000 square meters, will house cultural and commercial spaces, provide over 100 parking spots, and facilitate connections between Metro Lines 2, 12 and 13.

The project has attracted attention not least due to the dense layout of historic structures, including Zhangyuan's great hall, a 1928 building that once housed a night school for patriotic education in the 1940s, leaving little room for renovation or underground development. Zhangyuan's narrow lanes also demanded innovative solutions.

To overcome challenges, the construction team deployed advanced technologies, including mini-robots for pile foundation work. The self-walking, low-clearance drilling robots can be remotely controlled to navigate through narrow doorways and corridors, enabling foundation work within the historic structures.

The project team utilized building information modeling and point cloud scanning technologies to create detailed 3D blueprints, helping identify potential collision points and structural challenges.

They also developed specialized earth moving robots with folding mechanical arms that can operate in spaces less than 1.2 meters wide, using deep learning algorithms to distinguish between clay and obstacles.

"We designed multiple curved transportation routes for soil removal, implementing a factory-line-style system with track hoists and conveyor belts to minimize disruption while maintaining high efficiency," explained Zhang Yi, general manager of the urban renewal construction company of Shanghai Construction No 2 (Group).

Upon completion, the renewed Zhangyuan complex will integrate above-ground historical preservation with underground modern facilities, linking surrounding high-rises, shopping areas and neighborhoods, according to Shanghai Jing'an Real Estate Group Co Ltd.