The tunnel consists of 160 meters of covered trenches on the Dobrinja side, 340 meters of covered trenches on the Butmir side, and 340 meters of actual tunnel under the airport runway. On the Dobrinja side, the average height of the tunnel is 1.6 meters (excluding the height of the iron reinforcements) and averages 0.8 meters in width for the top half and 1 meters in width for the bottom half of the tunnel. On the Butmir side, the tunnel is slightly higher; 1.8 meters excluding the wood reinforcements. The width on the Butmir side is the same as that of the Dobrinja side. There is also a section called the 'reduced level entrance', a 30-meter portion on the Dobrinja side that was the deepest and most difficult stretch of the tunnel to construct. At its deepest point, the tunnel is 5m below the airport runway.