Big Bertha: How a Massive Tunnel Boring Machine Dug a Highway under Seattle

This incredible story about Bertha, the massive tunnel boring machine that successfully constructed the longest and widest road tunnel in the contiguous United States, under the city of Seattle, brought to life in vibrant and engaging illustrations, will appeal to kids ages 7-10 fascinated with big machines and how they work.

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...