Spatiotemporal evolutions of rail temperature on Guangxi railways and the influence of meteorological elements

Rail temperature serves as a core physical variable that characterizes thermally induced deformation of railway tracks, and it is significantly affected by meteorological elements including air temperature and solar radiation. Abnormal track deformation caused by extreme rail temperatures seriously endangers the safe operation of trains. Based on the observation data collected from 313 rail temperature stations of Nanning Railway Bureau from March 2022 to February 2025, as well as observational datasets from national meteorological stations and shortwave radiation products derived from ERA5 reanalysis data, this study analyzes the spatiotemporal distribution characteristics of rail temperature and explores the potential influences of air temperature, solar shortwave radiation and other factors on extreme rail temperature.The results are as follows. The rail temperature in Guangxi presents a spatial pattern of being low in the northwest and high in the southeast. The maximum rail temperature ranges from 49.8 ℃ to 71.1 ℃, while the minimum rail temperature is mainly concentrated between -7.6 ℃ and 6.9 ℃. The northeastern region features the coexistence of extreme maximum and minimum rail temperatures. Temporally, the monthly variation of rail temperature presents a unimodal pattern, with the peak value occurring in July and the trough value appearing in January or December. The daily maximum rail temperature primarily occurs during 14:00-16:00 BT. Rail temperature is highly correlated with air temperature across all seasons. Intense solar radiation leads to the most obvious difference between rail temperature and air temperature in summer, and the two variables maintain the most consistent numerical distribution in winter. Under different weather conditions, solar shortwave radiation on sunny days makes the peak rail temperature much higher than the peak air temperature, and the two peaks are the closest on rainy days. In addition, the increase of solar shortwave radiation can substantially elevate rail temperature, and the sensitivity of rail temperature to air temperature fluctuations decreases when the radiation intensity exceeds 750 W·m⁻². This research can provide theoretical support for railway operation safety and rail temperature forecasting under extreme meteorological conditions.