Geological and geotechnical studies were conducted on Segment 7, SBMA-Tipo Highway in Subic Bay Freeport Zone, Zambales to delineate areas of potential slope failures. The investigation involves examining in detail the geology of the highway and vicinity. and evaluating the geotechnical properties of the soils that underlie the roadcut slopes. To this end, field mapping of the different lithologies and structures were conducted. Several soil classification tests were also performed including moisture content, grain size analysis, and Atterberg limits. Direct shear test was used to determine the shear strength parameters of the soils. For slope stability analysis, the Bishop’s Method of Slices was applied,

Results of the study shows that of the seven slopes studied, two are susceptible to slope failures - slopes at km 4 + 360 and 6+080. Several geological and geotechnical factors contributed to the instability of the two slopes, among them: the low strength of the soils that underlie them; large amount of fine-grained materials and the presence of clay minerals with highly variable characteristics; high degree of weathering; weak parent materials; presence of discontinuities; and the presence of seepage. The high amount of rainfall, presence of a number of potential earthquake generators, and presence of volcanoes in the study area and vicinity were identified to be possible triggering mechanisms for mass movement. There are several ways by which the slopes can be stabilized. The general principle is to decrease the driving forces and increase resisting forces of the slopes.