The Chinese megacity of Shenzhen has successfully switched 100 percent of its 16,359-vehicle bus fleet to electric vehicles, reaching its goal just six years after it vowed to move away from diesel engines, according to reporting by CleanTechnica and other news outlets. The fleet — which has three times as many buses as New York City — serves a population of 12 million. The switch is expected to save the equivalent of 345,000 tons of diesel fuel and cut 1.35 million tons of carbon dioxide emissions.

To aid in the transition, Shenzhen, located in southeastern China, installed more than 300 bus chargers around the city that can recharge a bus’s battery in 2 hours. It also installed 8,000 streetlights that double as charging stations for both buses and cars. The switch was completed on December 27.

The program, launched in 2011 as a way to cut air pollution and reduce urban noise, was a costly one. Shenzhen spent $500 million on the switch in 2017 alone, a price tag that included both buying the vehicles and installing charging infrastructure. An estimated 80 percent of the buses were provided by electric automaker and lithium-ion battery manufacturer BYD, which is headquartered in Shenzhen.

The city is now working toward a goal of a 100 percent electric taxi fleet. Of its more than 17,000 taxis, 12,518 are already electric, CleanTechnica reported. It aims to finish the transition to EV cabs by 2020, if not earlier.