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The highway route Zagreb-Split, section through Lika region, was designed along the valley of the River Gacka. In this section the highway level line often crosses or goes along the contact zone between two lithological types. The significant differences of rock mass properties of two types would represent the geotechnical problem. The type of contact was also not known as well as the possible weathering degree. Investigation results showed no significant difference in characteristics between Cretaceous limestones and Eocene- Oligocene breccias. Using the results of comprehensive investigations engineering geologi- cal model was made.