If the city is compared to a container, then the city’s carrying capacity is not only determined by the city’s size and volume, but also by the city’s target objects. The objects are mainly composed of urban subjects, which are populations and human activities. The suitability of human activities in urban area depends on the city’s carrying capacity determined by natural factors, ecological environment, economic conditions, social management and others. The comprehensive carrying capacity of a city manifests as the coordination and balance between the city carrier and the carrying objects, and it is the organic combination of human activities and natural resources, environment, economy and social conditions.

The social and economic activities of a city should be compatible with its resource, environment, social and economic bearing capacities. When this balance is broken, environmental pollutions, traffic congestions and other urban diseases will be inevitably produced until the formation of a new balance.

Natural resource carrying capacity is the basis of urban and regional sustainable development. It is composed of natural resources (land resources, energy, etc.) and ecological resources (air, water, etc.), which determine the direction, scale and speed of human activities; this type of carrying capacity is more stable. Artificial environment carrying capacity is an indispensable carrier of human economic and social activities. It is composed of infrastructure (transportation, communication, power supply, underground pipe network, etc.) and social facilities (schools, hospitals and culture).

To take land as an example, let us look at the relationship between land and urban development capacity. In different stages of industrial development, there would be different functional characteristics of land to support the evolution of industrial structures. When the dominant force of economic development shifted from agriculture to manufacturing industry, the role of land in the production gradually transformed into the bearing function; when the manufacturing industrial development enters into the late industrialization or Information society, the functions the land’s value-added assets would become clearer. For this reason, we can see that the higher the rate of urbanization,

the more economically developed areas, the higher the land price will be.

This can also be seen from the efficiency of the service industry. In general, the amount of the land used for the agricultural industry is the largest and its utilization efficiency is the lowest. The land use amount of the manufacturing industry follows suit, but the utilization efficiency of the second industry shows obvious improvement. With the improvement of economic development level, service industry shows the trend of gradual increase in the output value. In general, service industry’s output increase value is faster than that of the manufacturing industry.

In addition, land bearing capacity and population size are closely related. Let us look at the carrying capacity of Chaoyang District in Beijing from the land perspective.

In 2012, the city’s total supply of state-owned construction land was 4115.3 hectares; 465 hectares of land was industrial and mining storage land, whereas residential land accounted for 1168 hectares, while infrastructure and other uses accounted for 2482.3 hectares. According to the Urban Land Classification and Planning Construction Standard promulgated by the Ministry of Housing and Urban-Rural Development implemented on January 1, 2012, the urban construction land index for capital city per capita planning should be determined within 105.1 ~ 115.0 m2 / person.

Based on the above criteria to analyze Chaoyang District and its streets as a whole and based on the statistics of the Sixth National Population Census and Chaoyang District Total Land Use Planning (2006 - 2020), Chaoyang District’s urban and rural construction land size is 26,801 hectares. If the land use standard is 105.1 square meter, the lower limit of Chaoyang District’s reasonable carrying capacity should be 2.55 million people. However, the reality is that, based on the resident population of 3.46 million, Chaoyang District per capita construction land area is only 77 square meters; according to the actual population of 420.7 million, Chaoyang District per capita construction land area falls to 64 square meters, and that is 60.7% of the national lower limit.

Once the land space is insufficient, traffic congestion, high population density and other issues will naturally appear. To some extent, the solution of these urban problems should be based on the comprehensive city carrying capacity.