Abstract: Nowadays, Salang highway is the major mountain pass connecting northern Afghanistan to Kabul province and southern Afghanistan. The subject of this research is to predict the frost penetration depth in north and south of Salang Highway. In order to reach this goal, field and laboratory soil data from 18 trial pits were collected and evaluated. Then Modified Berggren equation and Rajabei & Baladi formula were applied to predict frost penetration depth. The result of this study shows that average frost penetration depth in the south of Salang highway is 138 (cm) and it is 148 (cm) in the north of the highway. It is concluded that deeper frost penetration depth in the north part is because of more dry density and more thermal properties of soils with comparison to the south part. A correlation formula is developed between dry density of soil and predicted frost depth which makes it possible to predict maximum frost depth in Salang area and also other areas with similar geographic and climate condition.

Keywords: Frost depth, Salang highway, soil thermal properties, modified Berggren equation, dry density

| DOI: 10.17148/IARJSET.2020.7501