A preliminary cost estimation model for highway tunnel construction projects

Today, in the transportation sector, the approximate estimation of the tunnel cost before the start of production is important for the public budget and for the contractor. Although there are such many studies in the literature on the design/modelling, projecting and excavation systems and excavation support systems depending on the tunnel soil properties, there are few studies on the approximate cost. Based on the gap in this area, in various types of tunnels opened and manufactured with the New Austrian Tunneling Method (NATM), which is the most widely applied among tunneling methods; With the cost calculations of excavation and excavation support elements, an approximate tunnel cost model of the desired type, diameter and length in different soil classes, regardless of the duration, was created. In the model created with the parametric method based on Multiple Regression Analysis, using the support elements as parameters in the tunnel cost; (taking into account today's inflation differences) unit prices (KGM) for 2023 roads, bridges, tunnels, bituminous pavements, maintenance and traffic works are used. In the cost estimation model created with 35 observed and 5 control group different ground class tunnel data; for 1 anode length (12.10m), the coefficient of determination R2 = 0.997 and the mean error margin of 7,06% were calculated. With this model created, it is thought that benefits can be achieved in terms of both time and budget planning by making a fast cost calculation with a low margin of error. By using this method, the costs of a road tunnel of the desired length, using the relevant unit prices for the relevant time; It will be recalculated and provide temporal and cost benefits for both employer organizations and construction companies. The method has been found to be available for B1, B2, B3, C2 and C3 support classes. Keywords: Highway Tunnels, New Austrian Tunneling Method (NATM), Cost estimation, Excavation support systems in tunnels, Regression Analysis.