Three new lines will begin whisking passengers to and fro before the Games start in August and, by 2020, the route map will comprise 19 lines and 561 kilometers of tracks, making the network one of the world's largest.

CNN: Beijing commuters feel the squeeze

Of over 2, 200 climbers who have made it to the top of the world's tallest peak since it was first conquered, only 19 have done so via this route.

CNN: The height of teamwork on Everest

The 6, 000-mile route travels through Argentina and is due to end in Santiago, Chile, on 19 January.

BBC: Tom Neathway