In June 2009, sections of a gravel road situated in the middle of Sweden were stabilized with gravel and bio fly ash respectively. The aim of this study was to compare the different sections regarding stiffness and environmental impact. The environmental impact of the road was estimated from soil water and leachate from the road and an initial leaching of K, Na, Cl and SO4 was found from the lysimeters. The estimated total leaching from the road was not corresponding to the laboratory leaching tests performed on the ash (L/S10). The bearing capacity of the sections was measured with falling weight deflectometer at four different occasions and the bearing capacity increased with time and ash content. During snow-melting periods, the reference sections showed different disruptions but the test sections were unaffected. These results indicate that this fly ash seems to be suitable for gravel road stabilization.