An innovative high speed Weigh in Motion system for railway vehicles

The accurate estimation of the axle loads and the correct detection of overloads and imbalances, represent a primary concern for railways management companies, since they are strictly related to traffic safety and maintenance planning of the track. Weigh in Motion (WIM) systems aim at the dynamic weighing of railway vehicles through a reasonable number of measurement stations placed along the track. Such systems may overcome disadvantages in terms of costs and traffic management exhibited by conventional static weighing systems. In this paper the authors present an innovative algorithm for high speed WIM applications to estimate the wheel loads of trains by means of indirect track measurements. The formulation of the algorithm is quite general and it can be customized for several track measurements; consequently it can be employed in different typologies of measurement stations. The WIM algorithm processes the set of experimental physical quantities chosen as track inputs by means of estimation procedures based on least square (LSQ) minimization techniques. The vertical loads on the train wheels are computed from the measurements according to the assumption that the effects of the single wheel loads on the track are approximately superimposable. The whole WIM architecture has been developed in cooperation with Ansaldo STS and ECM SpA.