What happens under the ground? There are pipes, tunnels, and even roads below us. How are they built down there? In this book, young readers will learn about the methods engineers use to design and build fascinating underground tunnels, utilities, bridge foundations, and more! The Mi Biblioteca de Ingenieria/My Engineering Library series gives an introduction to a variety of engineering and design topics for beginning readers based on NGSS. From learning about how engineers design rockets to how they build structures underwater, these informative books present complicated information in easy-to-understand language with kid-friendly examples and diagrams. Each book includes a glossary, index, and an engineering design activity to support further comprehension.