The Copenhagen Metro, known simply as the Metro, was opened in 2002.

 

It currently has two lines and twenty-two stations, serving 120,000 passengers daily.

The trains are driver-less, and run entirely by a computer system called A.T.C or Automatic Train Control..

There are often Metro stewards on the trains, however, who provide passengers with information, as well as to handle any emergencies. 

If no steward is present on the train, passengers can call Copenhagen Metro Control  or C.M.C. from any call point on the train.

By letting a computer run the system, human errors are eliminated, and a low time interval between trains can be maintained. 
In the event of a failure of the ATC system, the trains can either be controlled remotely from the control centre or by the stewards on board.