Traditionally, manhole covers have been constructed of either cast iron, concrete, or even some combination of the two. This is because both of these materials are inexpensive, durable, and heavy enough to stay in place. However, similarly to manholes, technology has led to a variety of alternative manhole cover materials, including composite, fiberglass, and plastic. In this section, we discuss the many different types of manhole covers including cast iron manhole covers, plastic manhole covers, and composite manhole covers.