Reaching 68 meters deep with 25 levels and covering 390 square meters, this vertical parking garage can replace a 4,000-square-meter parking lot and hold 200 cars... Recently, Nanjing's first sunken-shaft parking lot began external operation. Located northeast of the Hexi campus of Nanjing Children's Hospital, this parking lot is currently the deepest sunken-shaft parking lot in the country and helps alleviate the hospital's parking difficulties.

To ease parking difficulties, many places in Jiangsu Province are exploring the use of underground space. By leveraging new technologies to revitalize idle plots and deeply tap underground resources, they are increasing parking supply. In Nanjing, in addition to the underground parking lot at the Children's Hospital, a sunken-shaft parking lot near Nanhu Square in Jianye District is also under construction and is expected to be completed and put into use by the end of the year or early next year, providing 100 parking spaces.

The sunken-shaft intelligent garage at the Children's Hospital has only an ordinary three-story building above ground, but there is much more beneath the surface. Below the building are two parking shafts with an inner diameter of 12 meters and a depth of 68 meters. Each shaft is divided into 25 levels, and each level can park 4 cars. The mechanical lifting platform can rotate 360 degrees to stop at any level, and cars automatically park in designated positions as if riding an elevator. The sunken-shaft parking lot uses an intelligent parking system and, through the lifting and rotating platform, enables vehicles to turn around inside the garage and enter and exit front-first, avoiding the need for drivers to reverse when leaving the garage and reducing parking difficulty.

According to reports, if built as a traditional surface parking lot, parking 200 cars at the same time would require at least 4,000 square meters. This sunken-shaft parking lot, however, covers 390 square meters and can meet the parking needs of 200 cars, expanding space utilization by more than tenfold. The site was originally a bus terminal, and the parking lot occupies only about one quarter of the original terminal space; the remaining space is still in normal use for bus parking. "The functions of the original site have not been affected. Of the three-story building above ground, in addition to the control room and equipment room, one floor serves as a 'replacement' for the original site function—the bus station office," said Yin Xiaolu, head of the Jianye District Parking Center. At present, the sunken-shaft parking lot handles an average of 160 to 180 vehicle storage and retrieval operations per day, with an average parking duration of 4.5 hours per vehicle. The charge is 6 yuan per hour, with a daily cap of 36 yuan.

The operation screen at the garage entrance displays the remaining parking spaces in real time. Click the "Store Car" button, and the car can be "in position" underground within 90 seconds. When retrieving the car, press the "Retrieve Car" button, and the lifting platform returns the car to the garage hall within 90 seconds, all controlled by the intelligent garage's "brain."

Chen Jun, director of the Security Department of the Hexi campus of Nanjing Children's Hospital, introduced that the Hexi campus handles 5,000 outpatient visits per day normally and up to 8,000 visits per day during peak periods, creating enormous temporary parking demand, but the surface and underground parking lots on campus can provide only 1,038 parking spaces. Because of parking difficulties, vehicles often formed long queues on roads such as Jiangdong South Road and Yiyue Street in the past. "The commissioning of this garage further facilitates patients visiting the hospital."

Urban development has entered the era of stock optimization, and parking difficulties are a common problem. Tapping underground space resources and increasing parking supply is a major trend that suits China's national conditions and aligns with modern urban development. Developing and utilizing underground space for parking services requires, at the construction level, mainly guarding against two major safety hazards: water seepage and fire. Current engineering technologies can address and resolve these issues. Engineering measures such as vertical excavation, mechanical operations, and disaster prevention and noise reduction are gradually becoming more complete, and supporting facilities and equipment such as high-speed lifts and intelligent control systems are also maturing. Projects such as sunken-shaft parking garages use machinery similar to subway shield tunneling for vertical construction, which not only requires a small construction site but also has less impact on surrounding residents. It is a technologically advanced construction method.

The underground silo-style vertical intelligent parking garage at Kunshan Forest Park has also been completed and put into use. A place that previously could accommodate 3 cars can now park 48 cars. The garage extends 17.85 meters underground and has 4 levels of underground mechanical parking spaces. It adopts a circular silo design with high space utilization; each level of the 22-meter-diameter silo has 12 parking spaces arranged in a radial pattern, with a turntable-equipped lift in the center. Related fire protection, ventilation, and strong- and weak-current conduits are laid along the curved edge area of the circular silo, achieving compact use of underground space and optimizing the value of underground space.

Various places are also exploring the creation of layered parking facilities and other ways to tap underground resources. Nanjing Xuanwu Foreign Language School developed and utilized the land resources of its sports field to build an underground parking lot. The four-level parking area not only meets the needs of teachers and students' parents but also opens spaces to nearby residents. Parking conflicts are relatively prominent in areas around some hospitals and old residential communities in Jianye District. Most areas in Mochou Lake and Nanyuan subdistricts were developed early and are highly developed, and there are currently no idle corner plots, while parking demand continues to increase. To solve parking difficulties, Jianye District is deeply tapping resources and putting underground space to use, building underground parking lots under the sports fields of Mochou Lake Primary School and Jianye Junior High School to ease surrounding parking conflicts. At present, the underground parking lot at Mochou Lake Primary School has officially opened, providing 71 public parking spaces. The underground parking lot at Jianye Junior High School will open this month, providing 105 public parking spaces. The underground parking lot at the Aonan campus of Nanjing Normal University Affiliated High School is also expected to be completed and opened this year.

This year, the Nanjing Urban Management Bureau is focusing on the annual livelihood target of "adding 10,000 shared parking spaces," guiding all districts to formulate the Three-Year Implementation Plan for Parking Resource Sharing (2023–2025), clarifying the three-year goals and direction, and encouraging all districts to adapt to local conditions and seek space above ground and underground to ease parking difficulties.

Using urban underground space to build vertical parking facilities and underground garages is undoubtedly one of the effective ways to alleviate urban parking difficulties. The sunken-shaft parking lot near Nanjing Hexi Children's Hospital adopts the prefabricated assembled sunken-shaft underground mechanical parking garage model, which occupies little land and has little environmental impact. This approach of using fragmented corner plots and releasing parking space is worth promoting. However, during construction, the scale and plan should be formulated according to geological conditions and parking demand, with overall management well coordinated to fully leverage parking efficiency while also taking into account humanistic and surrounding environmental relationships. He stated that in the context of urban renewal, there is still a lack of policy and regulatory support for how to use abandoned land and fragmented plots to build sunken-shaft parking lots. Guidance is needed from top-level planning design, and the interconnection between parking lots and surrounding facilities should be further strengthened.

Exploring the development and utilization of underground space for parking—whether to build sunken-shaft parking lots or underground layered parking facilities—should be decided according to local conditions, with full consideration of factors such as stratum structure, construction environment, and economic viability. Generally speaking, the greater the construction depth, the greater the difficulty and the higher the construction cost. Sunken-shaft parking lots are more suitable for locations with high road network density and many access intersections, such as parks and squares. If located around old residential communities, the patterns of parking demand should be fully considered, with emphasis on managing traffic flow well to avoid creating new traffic problems that affect residents' lives.