Construction works including the improvement of the existing tunnel with a length of 903 m, located at 27th km of TEM Yeniçağa Zonguldak road and construction of a new tunnel with a length of 1050 m and dimension of 12 m as the 2nd tube near the existing tunnel as well as the construction of entry-exit portals and roads
15th Regional Directorate of Turkish State Highways (TCK)-Kastamonu, Construction of II. Tube Tunnel - Dorukhan Tunnel Construction
