On the location Zagrad in Rijeka, Croatia, an open pit has been designed and constructed for the purpose of building the garageaccommodation- business complex. The location of the open pit is situated in the central area of the town Rijeka, and closely surrounded by the existing accommodation buildings, a traffic line and a railway. The open pit was designed and constructed four levels below the terrain surface, adjacent to the existing buildings and a traffic line. To secure the open pit walls during excavation, a support system with the selfdrilling rock bolts for the reinforcing of the rock mass and reinforced concrete grid structure on the excavated surface was designed. This paper presents the construction method for the open pit, with the application of active design concept during works execution. It also presents the set-up system for measuring, observing and monitoring of the support system behavior. This enabled, on the basis of the measurement results and performed back analysis, an active designing of the suitable support system during works execution, for the in situ conditions of the rock mass in excavation. Performed back analysis showed need for the additional correction in the correlation between deformation characteristics of the rock mass and rock mass classification
