The tunnel is part of the Gümüşova-Gerede Highway O-4 / E80 within the Trans-European Motorway project, which was carried out by the Turkish Bayındır and Italian Astaldi joint venture since April 16, 1993.[2] The total cost of the tunnel is about US$300 million. It has twin 17-metre-wide (56 ft) bores carrying three lanes of traffic in each direction.
The tunnel crosses the North Anatolian Fault. The November 12, 1999 Düzce earthquake (MW=7.2) caused substantial damage to the tunnel and viaducts, which were under construction at the time of the earthquake.[2]
On September 4, 2005 the excavation of the tunnel in the Istanbul-Ankara direction was finished. The excavation for the tunnel in the Ankara-Istanbul direction was completed by the beginning of August 2005.
Opening to traffic
The Istanbul-Ankara direction (3,014 m (9,888 ft)) was opened to traffic on January 23, 2007 by the Turkish Prime Minister Recep Tayyip Erdoğan and Italian Prime Minister Romano Prodi.[2] Four months following the initial opening, on May 7, the Ankara-Istanbul direction (3,125 m (10,253 ft)) became operational.[3][4]
Speed in the tunnel is limited to 70 km/h (43 mph).[5] Dangerous goods carriers are not permitted to use the tunnel.[6]