Big Bertha

Big Bertha tells the incredible story of Bertha, the massive tunnel boring machine that successfully constructed a road tunnel under the city of Seattle— the longest and widest one in the contiguous United States. Brought to life in vibrant and engaging illustrations by Katy Wu, this story will captivate kids who are 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. 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

Published by Little Bigfoot, an imprint of Sasquatch Books.

  • "Fueled by the drama of a subterranean breakdown and a race to the finish line, this big-machine tale is anything but boring."

    –Booklist starred review

More about Bertha….

This is Bertha before she began drilling the tunnel. To better understand her enormous size (5 stories tall!), find the man in the picture.
HINT: He is on the bottom right. Can you spot his white helmet?
Photo credit: WSDOT

Click on the links below to learn more about Bertha and the new SR99 tunnel that Bertha built. At the bottom of the page, there is also an experiment you can do to learn about how arches work, a technology used in the construction of Bertha’s tunnel.

Roof Shape Experiment

BUILD YOUR OWN ARCH!

How much stronger is an arch than a flat roof? Try this experiment to find out.

Supplies:

  • small box, such as a shoe box

  • several sheets of thin paper; plain printer paper or construction paper works great

  • a bunch of coins such as pennies

  • scissors

Activity:

  1. Build a flat roof by placing one sheet of paper across the top of the open box.

  2. Place coins, one at a time, on top of the paper. How many coins can the roof hold before it collapses? Record your answer.

  3. Build an arch by bending a piece of paper into an arc and placing the ends of the paper on the inside walls of the open box. You may need to trim your paper to the right width to make it fit.

  4. Place coins, one at a time, on top of the arch. How many coins can your arch hold before it collapses? Record your answer and compare it to the flat roof results.

  5. Build a double arch by removing the piece of paper and cutting it in half. Make two arches by bending the papers into arcs and placing them side by side inside the box to make them stand up next to each other.

  6. Place a third piece of paper on top of the arches for a platform. How many coins can your double arch hold? 

  7. Try making a triple or a quadruple arch platform. How many coins can it hold? Can it support a banana? How about a book?