Uplift-monitoring for dynamic assessment of electrical railway contact lines

Abstract

Although international railways have seen a massive increase in high speed rail there are still large amounts of older existing infrastructure designed for completely different criteria. The current supply systems of old electric railway lines, called soft catenary systems, are characterized by their design towards an optimal quasi-static behaviour. To increase the speed it is important to explore possible limiting factors, i.e. to identify the dynamic consequences and limitations. This paper explores a newly developed sensor system. Several sensors are placed over approximately 150 m to capture the dynamic behaviour. This is then used to create a base line for future monitoring as well as for assessing the possibilities of increased speed. For soft contact lines it is important to control maximum uplift at the pole support and the dynamic behaviour. The stiffness of the system changes between poles as well as along the section depending especially on track geometry; this makes it equally important to assess several other points between pole supports. Excessive vibrations can produce loss of contact rendering arching, increased wear and disrupted power supply. In the present paper acceleration time series were used to predict maximum vertical displacement, train speed, to assess the dynamic behaviour and to quantify modal parameters.