The weighing in motion or dynamic weighing system, from English Weigh In Motion (WIM), is a set of devices designed to measure and record weights per axle and weights per complete vehicle. Unlike static scales, dynamic weighing systems are capable of measuring without interrupting the flow of traffic and do not require the vehicle to come to a complete stop. There are countries that impose fines using this type of system on overweight vehicles in a very efficient manner.[1]​.

Knowing the total weight or axle weight of a vehicle has multiple uses, among them it is worth mentioning:.

• - Design and monitoring of routes, roads and bridges.

• - Research and development of new materials and techniques for the construction of roads and bridges.

• - Fines for excess weight.

• - Road legislation and regulation.

• - Road administration and planning.

Dynamic weighing scales are used to detect violations of vehicle sizes and weights allowed by regulations, and eventually the application of fines. The National Road Directorate is the one who establishes the maximum permitted according to current legislation in Argentina. In general, dynamic weighing systems are used to preselect overloaded vehicles. Subsequently, on a static scale, verified and enabled, the static weight is measured and, if applicable, the fine will be issued. In Argentina, when scales are used to fine overweight vehicles, they must be enabled and verified at INTI within the Legal Metrology Program[2]​.

In recent years, different variants of dynamic weighing systems have become increasingly common. One of them is on-board weighing, which is used to know at all times the weight supported by the axle. These systems are ideal to be applied to weighing and security in large load moving machines. Unlike conventional equipment, the sensor is installed in the vehicle.[3]​.

Dynamic weighing is also applied in rail transport. Some well-known applications are[4]​.

• - Rail protection (load imbalance or overload).