With the construction of viaducts, the number of ancillary spaces under viaducts is increasing, and the phenomenon of unreasonable use is troubling the city's appearance and residents' lives. As the city with the largest number of viaducts in the country, the use of gray space under viaducts is a topic of concern to many citizens. This design investigates the form and scale of Shanghai's main viaducts, the surrounding facilities and environment, and designs a shared box that adapts to the form of the viaduct and is suitable for the surrounding functional areas, improving the use of gray space under the viaduct.