Compactors are used to help build firm and stable foundations! Without good compaction, or highways, bridges, dams and buildings would not last! Compactors are very important pieces of equipment, helping us build things that are going to last for a very long time!
A compactor is a machine or mechanism used to reduce the size of material such as waste material or dirt and gravel through compaction. With fewer gaps between the particles, it makes it firmer, or more stable, allowing for a strong foundation to build a road, or even a skyscraper on.
In landfill sites for example, a large compactor with spiked steel wheels, called a landfill compactor, is used to drive over waste deposited by trucks, to cause the material to be pressed together so that it takes up much less space, making room for even more trash!