China has approved a 247 billion yuan ($36 billion) railway plan to improve transport links between the capital Beijing, the port city of Tianjin, and the neighboring province of Hebei, part of plans to integrate the three areas into a mega-city.

The National Development and Reform Commission said in a online statement on Monday that the plan will span nine projects that total 1,100 km (683 miles) long. These projects will be built over the years to 2020, and are part of a wider plan that will stretch to 2030, it said.

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The current population of the three areas is estimated at around 110 million, and by the time it’s complete, the so-called Jing-Jin-Ji project will span 212,000 sq km (82,000 sq miles), or more than twice the size of South Korea.