Construction sites are often overrun with enormous pieces of machinery, such as bulldozers, cranes and tractors. It takes a lot of power to convert virgin landscape into a skyscraper or neighborhood, which is why the necessary equipment is built large and durable. A single Caterpillar brand industrial loader that scoops up chunks of earth weighs more than 5,000 pounds (2,267 kilograms) [source: Caterpillar].
Before work can commence, equipment has to get to the construction site. Also, to get the job done probably requires more than a single industrial-sized tractor. Since it would take a while for a line of bulldozers to creep down the road, tow trucks or semi-trailers attached to tractor trailer cabs can do the heavy-lifting. Depending on the scope of the building project, a tow truck might have to transport several tons of construction vehicles to and from the site.