[1] 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.

It has twin 17-metre-wide (56 ft) bores carrying three lanes of traffic in each direction.

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.

[6] Media related to Mount Bolu Tunnel at Wikimedia Commons