BEIJING - Beijing will add six new subway lines or sections to its underground grid by the end of 2014 as part of efforts to ease traffic jams, subway authorities said at a press briefing on Tuesday.

A line that links suburban Changping district with Line No 8 will be constructed by the end of the year, according to sources with the Beijing Railway Construction and Management Co Ltd, the subway's constructor. The second phase of Line No 8 will also be finished within the year.

Four new lines, including the second phase of Line No 6, Line No 7, the east part of Line No 14 as well as the west part of Line No 15, will be put into operation by the end of next year, according to the sources.

Along with two sections that were opened earlier this year, a total of 84.8 km of subway will be put into use in the two years of 2013 and 2014.

As of May 5 this year, Beijing's subway length has risen from 114 km in 2007 to 456 km, accounting for 23 percent of the country's total and carrying approximately 10 million passengers daily.

By 2015, the number of subway lines in Beijing will reach 19, with a combined length of 561 km. By 2020, the total subway length is expected to have increased to 1,000 km.