Weigh-in-Motion Systems Review: Methods for Axle and Gross Vehicle Weight Estimation

Weigh-In-Motion (WIM) systems dynamically measure vehicle weight, eliminating the need for vehicle stoppage on static scales. These systems are the most convenient way to identify overweight vehicles, one of the main causes of pavement damage. In order to be employed for direct enforcement, WIM systems must provide accurate and reliable measurements, which is very challenging, especially due to the dynamics of the moving vehicles. Aiming to overcome these challenges, various methods to estimate the weight of moving vehicles have been proposed. This paper first introduces a comprehensive overview of Weigh-In-Motion systems, addressing sensor types, road surface quality, weather conditions, and calibration methods. Moreover, the review addresses the impact of dynamic loads – oscillating forces exerted on the road surface by moving vehicles – on system accuracy, considering vehicle properties, speed, and road surface quality. The focus of this work are the different Weigh-In-Motion estimation methods, which were divided into two sequential stages: instantaneous axle load estimation and Gross Vehicle Weight (GVW) estimation. Although there is extensive research on WIM systems, comprehensive reviews that simultaneously categorize and explore both instantaneous axle load and GVW estimation techniques are lacking. By investigating these two sequential stages, this review highlights the limitations and challenges of implementing accurate WIM systems and indicates opportunities for further advances.