Cutting traffic, pollution

Easing traffic congestion and other big city problems is one of the main reasons the capital chose to control the growth of new cars.

According to the municipal traffic commission, the annual growth of car numbers in Beijing has fallen from 44 percent in 2011 to 24 percent in 2017, which the government considers an obvious effect of the lottery policy.

The capital's traffic index in 2017－a major gauge measuring traffic congestion－remained roughly the same as it was in 2016 at 5.6, standing for mild congestion. In 2010, the index was 6.1, showing a level between mild congestion and enormous congestion.

However, according to Tom-Tom Traffic Index, an international information provider, Beijing ranks 10th on the list of the most congested cities in the world and drivers in Beijing spent 46 percent more travel time in 2017 as a result, up 8 percent from 2016.

Reducing emissions is another municipal concern. Vehicle exhaust is the top source of PM2.5－the hazardous fine particles in Beijing's air, based on an analysis from the Beijing Environmental Protection Bureau in 2014, the latest numbers available.

It accounted for 31.1 percent of PM2.5, higher than the amount discharged from coal-consumption and industrial production, it said.

"Beijing has taken effective controls and managed to cut the pollution from vehicle exhausts in the past five years, which fueled the improvement of the air quality," Li Xiang, director of air quality management at the Beijing Environmental Protection Bureau, said on Jan 4 while releasing Beijing's air-quality report for 2017.