Beijing will invest 100 billion yuan ($16 billion) in the coming years to expand its subway lines, Deputy Mayor Chen Gang said on the sidelines of the ongoing 18th National Congress of the Communist Party of China on Friday.

The subway expansion will make it possible for people to live farther from their jobs, helping optimize the city’s layout and relocate downtown residents, Chen said.

"It will also aid our efforts to cut car emissions and improve the environment."

The capital's subway system, which already cost 260 billion yuan will gain another 70 km of rail by year-end, bringing the total to 442 km.

Chen said trains are the answer to traffic gridlock in metropolises such as Beijing, which now has more than 5 million vehicles, a number that continues to rise rapidly. To counter that, the city initiated a license plate lottery system that allows only 240,000 applicants to register a new vehicle a year.

The capital has also been steadily expanding and updating its bus fleet. By the end of 2011, Beijing had more than 28,343 buses carrying over 13.39 million person/trips a day.

To further improve bus efficiency, the city has designated bus-only lanes on certain roads.

These measures are showing results: 42 percent of commuters chose public transportation in 2011, and the percentage of people driving cars dropped for the first time.