Too late snow wall removal as an enabler of rapid edge deformations - results from Aurora instrumented road sections on road E8 in Finland

Since early spring 2018 Tampere University and Roadscanners Oy have conducted long term structural and functional monitoring of two road sections on road E8 in Muonio, Finnish Lapland. This monitoring has been part of the Aurora project, an open testing ecosystem of intelligent transport and infrastructure solutions launched by the Finnish Transport Infrastructure Agency (FTIA). One of the unique observations made based on monitoring the vertical strains of base course layer and the vertical displacement of road surface concerns abrupt frost heave that takes place in the upper part of pavement structure in late spring before the start of thawing period. The phenomenon coincides with the melting of snow next to road edge, which indicates that the source of water enabling this late spring frost heave is from the side of road, not through the deeply frozen structural layers below. The conclusion was verified by means of periodic GPR measurements applied in monitoring the water content of road structure. The above observation emphasizes the importance of early enough removal of snow walls from road shoulders as a means of limiting the edge deformation and rutting of road structures during the thawing phase of seasonal frost.