Observation and Prediction of Trolley Wire Frosting in the Railway Field

Abstract

To investigate trolley wire frosting phenomenon, the frost formation was observed and its meteorological conditions were analyzed. As a result, the probability of frost formation was high when the following conditions occurred at the same time: air temperature below 0.5°C, relative humidity above 80%, wind speed less than 1 m/s and net radiation −120∼−70 W/m2. It was ascertained that the water vapor was supersaturated in the neighborhood of the trolley wire surface. Next, experiments on trolley wire frosting in a cold room were carried out. It was confirmed that the growth rate of the frost was proportional to supersaturated water vapor ratio. Finally, based on the observations and mechanism of frost formation, we examined a prediction method for the formation of trolley wire frost using air temperature and relative humidity in the evening, and the forecasted weather conditions and the minimum temperature in the next morning. It was confirmed that accuracy of predicting the trolley wire frosting by this method was higher than the experientially used method.