In 2013, construction crews raced to replace a crumbling elevated highway along Seattle's waterfront with a double-decker tunnel running almost two miles under the city. This is the story of Bertha, the mammoth and complex tunnel boring machine that simultaneously dug and built the tunnel, and Deputy Project Manager Greg Hauser and his dedicated crew.

Kids interested in engineering and how machines function will love learning about the tunnel boring machine, how it worked, and how Bertha's crew solved problems that arose along the way to ultimately construct an amazing, earthquake-safe highway under the city.

In addition to the narrative story the book includes additional information about Bertha and this fascinating engineering feat, including:

• Facts about Bertha and the tunnel
• How Bertha simultaneously dug and built a tunnel
• Engineering background about the tunnel's construction