Snow and ice can accumulate between the moveable parts of a switch point during the winter season. As a result he point cannot be switched anymore. In order to prevent failures and delays of trains, switch points are heated. Electrical heating rods shall ensure the melting of snow and ice in the critical areas of a point. Practical experiences have shown that this is not always possible. A calculation model for the heating of a point has to be set up in order to investigate the effectivity of switch point heating systems. Besides that, various ambient factors (such as ambient temperature, wind, precipitation) reduce the heating of the point. However, the extent of impact of the weather conditions on the heating remains to be investigated. Therefore, it is important to study their thermal influence and implement it into the calculation model. The Thermal Network Method (TNM) is suitable in this case. Initially the single main components of a switch point will be set up in separate networks. After a verification with experimental setups, the separate networks can be connected to each other. An experimental setup of an entire model point gives the opportunity to compare calculated and measured heating results without the influence of weather conditions. Finally, the ambient conditions can be implemented into the TNM model by performing field tests. The finished model can give high-resolution temperature information for different heating powers, ambient temperatures, wind velocities, rain and snowfall. According to the practical experience of various railway companies the temperature distribution is calculated for different parameter scenarios and subsequently evaluated regarding its effectivity to prevent failures.

Thermal Network Method; point failure; heating calculation; varying ambient conditions