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

Rail temperature is a key physical variable governing thermally induced deformation of railway tracks, and it is strongly affected by meteorological elements including air temperature and solar radiation. Abnormal track deformation caused by extreme rail temperatures poses a serious threat to railway operational safety. 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, this study analyzes the spatiotemporal characteristics of rail temperature and explores the influences of air temperature, solar shortwave radiation and other factors on extreme rail temperature.The results are as follows. The rail temperature in Guangxi exhibits a distinct spatial pattern, with lower values in the northwest and higher values in the southeast. The maximum rail temperature ranges from 49.8 ℃ to 71.1 ℃, while the minimum rail temperature ranges from −7.6 ℃ and 6.9 ℃. Northeastern Guangxi experiences both extreme maximum and minimum rail temperatures. Temporally, rail temperature displays a unimodal annual cycle, peaking in July and reaching the minimum in January or December. The daily maximum rail temperature typically 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 temperature are generally consistent in winter. 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. When radiation intensity exceeds 750 W·m⁻², increase of solar shortwave radiation can substantially elevate rail temperature, and the sensitivity of rail temperature to air temperature decreases. These findings provide a scientific basis for rail temperature forecasting and for ensuring railway operational safety under extreme meteorological conditions.