Road salt is used in Norway to improve safety by increasing friction on icy roads. Given the adverse environmental effects of using road salt, it is important to know that the assumed safety effects are realised.
The use of road salt should also be informed by important contextual factors. For instance, the increase in accident risk when driving on snow or ice-covered roads is greater in those areas where such driving conditions are encountered less often.
Furthermore, road salting leads to better friction and thus increased speed. One is therefore faced with two optimization issues: a) what is the increase in risk on the remaining or surrounding unsalted snow or ice- covered roads when salt has been used on parts of the road network, and b) does the speed increase from road salting increase the number of more serious road accidents?
Norwegian studies of the effects of road salting are old and need updating, not least to account for the above optimization issues.
Safety effects of road salting in winter road maintenance, TØI Report 1171/2011, Author: Torkel Bjørnskau