Load securing is the practice of stabilizing and securing cargo so that it remains stationary during transport. This is done for several reasons but especially to prevent the cargo from being damaged. Load securing also prevents damage to the vehicle carrying the cargo or loss of the cargo itself. The practice is common in all facets of the cargo and transportation industries and can take many forms depending on the type of vehicle and the type of cargo being transported.
Four main types of transportation are used around the world to haul cargo. Cargo planes, trucks, trains and ships are the primary means by which most cargo is transported. Some methods of load securing are specific to each type of transport, but some are common to all of them.
Simple tie-downs are the most primitive and still one of the most common types of load securing for smaller cargo loads. Ropes, high-strength straps, and cables are used to hold the load in place with the ends tied to grommets, eye-holes, or any available part of the cargo vehicle. This simple type of load securing has been used to move cargo for thousands of years, on horses, camels, and archaic vehicles, like wagons and sailing ships.
In modern times, many specialized techniques for load securing have been developed. Boxes arranged on pallets in such a way that the palletized loads form regular shapes are called unitized loads. The load and the pallet are then tightly wrapped in plastic, stabilizing the individual boxes and securing them to the pallet itself. These unitized loads are sometimes further stabilized by strapping them.
A common device in load securing is the come-along. This is a type of ratcheting fastener that gradually tightens a strap until it is much tighter than could be achieved by simply pulling on the strap by hand. The strap may or may not be attached to securing points on a vehicle, as these types of straps are sometimes used to stabilize small loads on pallets as well. Some types of come-alongs may also be used on chains or cables.
Large cargo loads may be secured by a number of other means. Blocking is a technique by which wooden blocks are nailed or bolted to the cargo vehicle to stabilize a load. Dunnage is the practice of surrounding cargo with other items such as wood or waste materials to fill any spaces between the various loads and the vehicle, stabilizing the cargo. Dunnage bags are a relatively recent invention that were first used in the 1960s and are essentially balloons of durable material placed around cargo and then inflated, immobilizing the load.
Modern cargo containers and their transport have resulted in the development of an entire system of load securing devoted to these cargo carriers, which have become the standard for international shipping, particularly across the oceans. The containers lock together and to the deck of the ship with special locking fasteners installed on each container and the ship. These are often automatic, so the simple act of stacking the containers with a crane will lock them together.