As urban scales continuously expand, the mileage of roads and rail transit lines has rapidly increased, with various rapid transit facilities often adopting elevated forms. While initially aimed at alleviating urban traffic congestion, these viaducts have also brought numerous issues: they alter the city's original appearance, create negative gray spaces, fragment urban space and cultural continuity, and even breed new social problems. The rational and efficient utilization of the space under urban viaducts can, to a certain extent, effectively meet citizens' growing demand for public space and tap into the potential of urban space. Currently, cities such as Beijing, Guangzhou, Chongqing, Shanghai, and Shenzhen have not only introduced relevant policies but also implemented many successful cases of under-bridge renovation and utilization.