Civil engineers design and monitor construction projects like roads, buildings, dams, bridges, and sewage treatment and water supply. They try to build these structures in the most efficient and cheapest way. Civil engineers est soils and the strength of building materials, such as concrete, asphalt, or steel. They give cost estimates for materials, equipment, or labor. They use software to plan and design the structures that they are building. Some civil engineers design, some build and some supervise.