Template: Infobox trunk road / Maintenance / TR -O
Il ( provinces ):
The otoyol Highway 4 ( Turkish Anadolu Otoyolu, short O -4 ) is a highway that connects the cities of Istanbul and Ankara.
The highway is expanded to three lanes on both sides. Built in 1990-2007 street closes in Istanbul at the O -2 and O- ends at the 20th At the connection points Samandira, Kurtköy Sekerpinar, Gebze, İzmit Batı and talk lead feeder road with two lanes in each direction.
The highway includes six tunnels, of which the Bolu tunnel near the town of Bolu with 3,200 meters, is the longest.