Orhangazi_Tunnel
The Orhangazi Tunnel (Turkish: Orhangazi Tüneli), is a motorway tunnel located at Samanlı Mountains in Marmara Region as part of the Istanbul-Bursa Motorway 
O-5 in Turkey.[1]
Situated northeast of Orhangazi town between Laladere and Yeniköy villages on the province border of Yalova and Bursa,[2] it is a twin-tube tunnel of length 3,586 and 3,591 m (11,765 and 11,781 ft) carrying three lanes of traffic in each direction. The construction works began on 15 February 2012,[2] and are being carried out by Otoyol A.Ş., a consortium of Turkish Nurol, Özaltın, Makyol, Yüksel, Göçay and Italian Astaldi companies.[3] The New Austrian Tunnelling method (NATM) was applied for the boring of the tunnel.[4][5]
Breakthrough in one of the tubes was achieved on 19 February 2014 after two years and four days of work. A related ceremony was held at site in presence of Deputy Prime Minister Bülent Arınç and Minister of Transport, Maritime and Communication Lütfi Elvan on 3 March 2014.[5] It is the longest motorway tunnel of Turkey.[1][3][6] The tunnel's opening to traffic was in April 2016.
Other tunnels on the route are the 1,192 and 1,303 m (3,911 and 4,275 ft)-long Selçukgazi Tunnel and the 1,556 and 1,653 m (5,105 and 5,423 ft)-long Belkahve Tunnel.
