The city of Harbin’s Acheng district, in Heilongjiang province, has stopped more than 130 private cars from offering unlicensed taxi rides in a campaign against these “black”, or unlicensed taxis, Heilongjiang Daily reported on July 9.

The campaign began earlier this year under transportation authority supervision to protect the licensed taxi drivers and avoid any risks and hidden dangers in the unlicensed car operations. They employed various methods to root out the violators, for example, working round the clock in shifts to inspect vehicles at checkpoints across the district, especially in densely populated or large residential area, and near schools, bus depots, and hospitals.

The number of private cars the district has ballooned in recent years, and some of the owners began to get involved in commercial transactions, which the city says can disturb market order.