The World's Largest Tunnel Boring Machine: A 400-Foot, 9.5-Million Pound Mechanical Earthworm

We've been thinking a lot today about moving earth to make pathways. Tunnels. What if you're not talking about thin, dirt tubes to move humans, though, but holes so big entire industries can flow through them? This is the world's largest tunnel boring machine: an Earth Pressure Balance (EPB) Shield developed by Herrenknecht AG.

Mainly for use in soft ground, like a giant earthworm, this thing's an earth-devouring beast: It's 51 feet in diameter, 400 feet long, weighs 9.5 million pounds, and requires 12,000 kilowatts to run its massive cutterhead. The EPB keeps an equal rate of soil removal and forward movement to ensure the soft ground overhead stays in place. It uses a combination of tungsten carbide cutting bits, carbide disc cutters and hard rock disc cutters to bore away.

The mammoth tunneler took three months to build and is expected to finish its first job (in Italy) in 2013, creating two 1.5 mile tunnels between Bologna and Florence and allowing for the transport of 90,000 vehicles per day. [Herrenknecht]
