Beijing authorities say they will ensure the city has a maximum population of 23 million residents by 2020 by reducing residents in six of its downtown districts starting this year.

The crackdown on population growth is part of Beijing’s five-year economic and social development plan.

Beijing aims to reduce the population in Xicheng, Dongcheng, Chaoyang, Fengtai, Haidian and Shijingshan by 15 percent below 2014 levels, which is about 1.92 million fewer residents.

Beijing-based factories, markets, education and medical institutions have already been pushed out of the downtown core through the use of economic and administrative measures, with a notable example being Beijing’s own municipal government.

Beijing authorities are also capping a number of other areas, including limiting urban construction to no more than 2,800 square kilometers, limiting yearly water consumption to 4.3 billion cubic meters and ensuring the city’s annual energy consumption meets national standards.

Beside overpopulation, Beijing suffers from other urban problems such as traffic congestion, rising property prices and the deterioration of the natural environment.

Lu Yan, director of the Beijing Municipal Development and Reform Commission, already has a solution to the first problem. Lu said Beijing will build a 900 kilometer-long metro system with stations that commuters can access with just a 750 meter walk from anywhere in the downtown core.

After having quadrupled in size in ten years, Beijing will continue to expand in a future amalgamation that will see it combine with Tianjin and parts of Hebei to become a megacity of 130 million residents. Estimated to cost some 42 trillion yuan, infrastructure for the new megacity have already begun in the form of a new airport.