Distribution of Road Conditions and Road Temperatures in Finland as Kilometres Driven

Road conditions and surface temperatures are known to influence the abrasion rate of road vehicle tyres. Tyre abrasion has the side effect of generating tyre and road wear particles belonging to microplastics that end up in soils and sediments. Therefore, it is necessary to know when, where and under which conditions vehicles drive to understand tyre abrasion.

This study examined the prevalence of road weather conditions and road temperatures in Finland as vehicle kilometres driven. The distribution of conditions was estimated for main roads using road surface sensor data. The estimate for regional and connecting roads and urban street networks was derived from the main roads estimate with input from road weather experts.

The results show that the most prevalent road condition on Finnish roads as kilometres driven is a dry road surface (56%), followed by wet and moist surfaces (29%). However, wintery conditions such as snow, ice and sleet still account for a large presence overall (12%), and especially during winter months (38%). 26% of annual vehicle kilometres are driven on surfaces below zero degrees Celsius. The distribution of conditions and temperatures is influenced both by time of the year and geography, with winters being at least partially snowy in the whole country and much colder and snowier in the north. The main result of this study is that the share of conditions in the annual kilometres driven in Finland are influenced by road class, geographic location and seasonal variation.