Changing temperate climate conditions for winter roads in the twenty-first century (Lithuanian example)

It is undeniable that winter weather is the most dangerous for all road users. Temperate climate creates winter weather conditions that are definitely challenging for road maintenance specialists: one year can be excessively snowy and relatively warm (high daily accident risk and maintenance costs), while the other would be cold and dry (lack of preparedness, lower maintenance, but higher standby costs). Therefore, with ongoing climate change, it is uncertain what weather can be expected in the future, especially with current predictions claiming climate change will bring higher variability and more frequent weather extremes. In order to estimate future impacts of climate change to road conditions (and traffic safety) during temperate winter, an analysis of climate model predictions was performed, using Lithuania as an example of such climate conditions. The focus of this analysis is on meteorological variables that are unfavourable for roads: number of days when air temperature fluctuates around 0 °C, number of days with snow and number of days with adverse driving conditions. Several time periods were chosen: reference (1986–2005), near-term (2016–2035) and long-term (2081–2100). The projections were made using Coupled Model Intercomparison Project Phase 5 (CMIP5) outputs of 4 Representative Concentration Pathways (RCP2.6, RCP4.5, RCP6.0 and RCP8.5). The data outputs of 3 global circulation models (GFDL-CM3, NorESM1-M and HadGEM2-ES) were statistically downscaled for meteorological stations in different regions of Lithuania in order to create distribution maps of climatic variables in the twenty-first century. Results showed that winter driving conditions should improve, and maintenance levels should decrease by the end of the twenty-first century. Nevertheless, a possibility remains that road maintenance and traffic safety might become less effective due to lack of awareness and preparedness, resulting in sudden and unexpected worsening of driving conditions on a day to day basis.