1 Executive Summary
Weigh-in-motion (WIM) is a technology that can be used for various private and public purposes (i.e.
applications) related to the weights and axle loads of road and rail vehicles. WIM systems are installed
on the road or rail track or on a vehicle and measure, store and provide data from the traffic flow and/
or the specific vehicle. For WIM systems certain specific conditions apply. These conditions have an
impact on the quality and reliability of the data measured by the WIM system and of the durability of
the sensors and WIM system itself.
WIM systems measure the dynamic axle loads of the vehicles and try to calculate the best possible
estimate of the related static values. The WIM systems have to perform unattended, under harsh traffic
and environmental conditions, often without any control over the way the vehicle is moving, or the
driver is behaving. As a result of these specific measurement conditions, a successful implementation
of a WIM system requires specific knowledge and experience.
Over the past decades, a vast amount of scientific and practical experience has been gathered on
the development, installation and operation of WIM systems. However, these experiences often come
in the form of technical scientific reports, which are typically not accessible or understandable to
a novice user of WIM systems or data. They often lack the answers that a WIM user is looking for.
Consequently, the International Society for Weigh-In-Motion has decided to develop a document
providing basic, yet a comprehensive introduction to WIM.
This document covers different aspects related to the working, specification, purchase, installation,
testing, operation and maintenance of WIM systems, and the application of the data they produce.
To enhance accessibility for users starting with WIM, these topics are described in an easy-tounderstand language. This means that sometimes a simplified description is given that may not be
completely in line with the latest scientific results. For those interested in more detailed and scientific
explanations, references to these detailed reports are included.
1 Executive Summary