Four new subway sections in Beijing have entered their final phase, the comprehensive debugging needed before they can open as planned by the end of 2014, the city's top urban planning authority said.

The work adds 43 new stations that will extend the current subway network by 62.6 kilometers, pushing the lines' total length to 527.2 kilometers, the Beijing Municipal Commission of Housing and Urban-Rural Development said on Thursday.

The construction has gone smoothly, the commission said.

The four sections are: the second phase of Line 5, going from Caofang to the east part of the city; Line 7, extending from the Beijing West Railway Station to the east; Line 14, going through areas between the East Third and Fourth Ring Road, as well as linking it to Lines 15 and 6; and the western section of Line 15, running through the areas between the North Fourth Ring Road and the Fifth Ring Road.