Patterns of residual salt on road surface : Case study

A field study was performed in order to investigate the patterns of residual salt on a road surface and the mechanisms involved in transporting the salt off the road into the roadsides. The residual salt was measured in nine segments across a road and repeated in 2-24 hour intervals, depending on the road surface conditions. The results will be implemented in a winter maintenance management model under development by the Swedish National Road and Transport Research Institute (VTI). The results showed clearly that the vehicles are important for redistribution of the salt from the wheel paths. A light snowfall increased the salt content in the roadway, probably because of redistribution of salt from outside the road border lines by passing vehicles due to increased wetness. The amount of residual salt in the wheel paths could be modeled rather well using an exponential function, where the amount of salt was depending on the accumulated number of vehicles after each salting occasion. A model constant was suggested to be related to the road surface conditions.