Digging underground in some of the world’s worst tunneling conditions is no easy task. To help relieve Kuala Lumpur’s constant gridlock, tunnel boring machines are digging and building almost 20 kilometers of tunnels for the city’s new mass rapid transit. Discover how the innovative Variable Density Tunnel Boring Machine was developed, put into action and overcame challenges to construct a key component of Malaysia’s new urban transport system. (thetvdb.com)