Super Tunnel Preview
Preview: Season 43 Episode 17 | 30s
Underneath the streets of London, a team of more than ten thousand construction workers race to build a brand new metro line—Crossrail. Costing almost $23 billion, it’s the biggest engineering project in Europe and must link into the existing metro system. As they burrow the 26 miles of tunnels, engineers battle to ensure historic buildings don’t crack and London Underground trains keep running.