Beijing plans to install more than 3,000 devices to monitor the operation of elevators and escalators in its subway system by the end of this year, Mirror Evening News reported on Thursday.

The monitoring device, called a black box for elevators, has a sensor attached to the elevator or escalator. The sensor is connected to the Internet and elevator maintenance workers' cellphones and can issue real-time warnings when the machinery malfunctions.

The sensors also monitor operations around the clock, and can alert maintenance workers of possible problems that might be caused by aging parts.

The devices can also analyze any malfunctions.

The elevator black boxes are expected to go into operation in the Beijing subway by the end of the year and cover all ascending escalators and elevators, the city’s administration of quality and technology supervision was quoted as saying.

A fatal accident occurred in the capital in subway Line 4 in July 2011 when an ascending escalator reversed suddenly, killing a 13-year-old boy and injuring 30 others.