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| Target layer | Code layer | Index layer | Indicator meaning | References |
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| Level of UUS development (D) | Construction of UUS (D1) | Development intensity of underground space in the built-up area (D11) | The ratio of the construction area of underground space development in built-up areas to the area of built-up areas is an important indicator to measure the orderly and connotative development of underground space resource utilization. The higher the development intensity, the higher the economic benefits of land use. | [1, 2, 5, 7] |
| Scale of underground space per capita (D12) | Per capita ownership of UUS construction area is an important indicator to measure the level of UUS construction. | [4, 7, 8, 11, 20, 21] |
| Parking underground rate (D13) | The ratio of urban underground parking spaces to the city’s actual total parking spaces is an important indicator to measure the functional structure of UUSs and the rational allocation of infrastructure. | [30, 35, 37, 39] |
| Comprehensive utilization rate of underground space (D14) | The proportion of urban underground public service space to the total scale of underground space measures the degree of comprehensive utilization of UUS market-oriented development. | [10, 12, 18–20] |
| Underground space social dominance rate (D15) | The ratio of urban ordinary underground space to the total underground space is an index that measures the degree of social and policy-led development of UUS development. | [8, 10, 12, 16, 17, 19] |
| Urban economic development indicators (D2) | GDP per capita (D21) | GDP per capita is an effective tool for people to understand and grasp the macroeconomic performance of a country or region and is often used as an indicator of economic development in development economics. | [42–45] |
| Urban housing prices (D22) | Urban housing price is a measure of the value of urban land. | [15, 16, 18, 19] |
| The proportion of the tertiary industry (D23) | The proportion of the tertiary industry is an indicator to measure the amount of building development of the city’s tertiary industry. | [39, 41] |
| Population attractiveness index (D24) | Using the city’s resident population attractiveness index, the ratio of the new inflow resident population to the new inflow resident population in all cities across the country is expressed, and the urban development trend is objectively presented. | [39–41] |
| Urban population index (D3) | Urbanization rate (D31) | It is a measure of urbanization. | [14–16] |
| Urban population size (D32) | Within the urban area, the total population is counted according to the permanent resident population. | [9–11, 37, 38] |
| Human activity intensity (D33) | Urban night light value intensity can be used as an effective form of representation of human activity. | [39, 41] |
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