The Sv. Ilija tunnel, 4.1 km long with longitudinal alignment gradient of 2.5%, was designed and constructed to improve transport links of the Makarska Riviera with the rest of the roads in Croatia. This traffic connection between the Makarska seaside and the A1 highway: Zagreb-Split-Ploče will carry up to 8600 vehicles/day as compared to the current number of 3000 vehicles per day (estimates for the year 2026). The longitudinal ventilation system with adequate improvement was installed by building service tunnel connected to the main tunnel tube every 700 m for fire trucks and every 250 to 300 meter distance for pedestrian crosswalks. The main building (geotechnical) project was developed by SMAGRA Ltd. Zagreb. According to the Traffic study (IGH, 1999) expected construction costs amount to 428.000.000 HRK. The estimated construction cost value based on the main construction project is as follows: a)main tunnel – 320.728.00 HRK and b) service tunnel – 64.145.000 HRK (7,5 HRK = 1,0 EUR). The main construction project for the building permit consists of eight books Phase I and thirteen books Phase II (installation projects). The building permit for the tunnel construction
was issued on February 19, 2001. The construction of the tunnel was completed and handed over to the operator for use in 2013.

tunnel, main construction project, geotechnical project, engineering geology, rock mass