In North America, a roll-off is a usually open top dumpster characterized by a rectangular footprint, utilizing wheels to facilitate rolling the dumpster in place. The container is designed to be transported by special roll-off trucks. There are two types of delivery trucks for the bins based on bin size and they are: Hook lift bins and Roll-off bins. Roll-offs are commonly used to contain loads of construction and demolition waste or other waste types. While most roll-off containers have a swinging door on the end for easier disposal of waste, some roll-off containers are not open top and are used with commercial or industrial trash compactors. Construction debris may originate from a building site where something is being built, renovated, or demolished. Roll-off dumpsters are also used for various jobs that need much material to be taken away. The material in the roll-off may be taken to a landfill, recycled or disposed/recovered of in some other way. Size Roll-off containers have a rectangular footprint typically determined by the size of typical trucks. Roll-off container sizes are determined by the amount of debris they can hold, measured in cubic yards. Typical container sizes in the United States are 10, 15, 20, 30, and 40 cubic yards(, , , and ) (or in other nations). While the roll-offs may be rented by volume, there may be weight limitations. Weight limits may be necessary to ensure compliance with road-use and safety laws and regulations. Most roll-off providers will have a weight limit for each container size. Containers loaded with more weight than allowed typically will not be hauled away due to safety reasons. Containers that are overloaded can result in damage to the roll-off truck and the road it drives on. The maximum weight is specified at the beginning of the job. In cases where the material to be disposed of is especially dense, such as dirt, rock, or concrete, a container with lower sidewalls is used. This is to help reduce the risk of exceeding the weight limit. The standard weight limit determined by the department of transportation is not to exceed ten (10) tons of debris. Operation After the container is picked up, it is taken to a disposal facility where it is weighed before (gross) and after (tare) dumping. The difference is the net weight, and is used to calculate charges to the customer. For efficiency, some facilities pre-record