The tunnels are required for environmental reasons and will be dug in at 30m underground.
The total length of the highway stretch will be 65km. The projected cost is BGN 1.7bn (USD 1.2bn).
"This is the longest tunnel facility in Europe and the second longest in the world," said the Minister of Regional Development Desislava Terzieva at a press conference.
According to Terzieva the tenders for the construction will start by the middle of this year and will continue through 2014.
