The entrance of the tunnel is situated on the 50 - 18 eastern longitude and 32 – 1 northern latitude. Its exit is situated on the 50-15 eastern longitude and 32-29 latitude, on the Zagros mountain range in Iran. The access route to the entrance of the tunnel has been asphalted for nearly 200 km and the remaining 40 km has not been asphalted yet. An extra 10 km road has been constructed giving access to the tunnel exit.
This project is being carried out at a height of 2100-2400 metres above sea level and its highest point can reach 4000 metres above sea level. The tunnel is 22570 metres long and its entrance is situated at 2200 metres above sea level in the Kuhrang Valley and its exit is situated 22+570 kms at a height of 2182 metres above sea level in the Zayand-e Rud Valley.

Geology
The area under study is 1400 square kilometres. The northern and north eastern boundary ends at the Zagros expulsion area, and in the south and southwest, it joins the northern regions of the Zard Kuh mountain. The region’s oldest ridges consist of the stone blocks of the Palaeozoic Era’s Cambrian period, which have resulted in the formation of salt domes. Sediments from the Mesozoic era’s Late and Early Cretaceous period have been identified in this region. The most important ridges are related to the lime stones of the Cretaceous period and they have created high mountains. The sediments of the late Mesozoic era can be seen on the mountain tops and those of the Early Cretaceous can be seen on the plains separating the mountains.

Hydraulic Specifications

After the completion of construction work, the third tunnel has to operate under two different hydraulic conditions. From the 0+00 km to the 3+432.8 km, the tunnel has an 11000 adverse slope with a 3.5 metre diameter. As a result, the tunnel will work under pressurized conditions. From then on there is a 15 % adverse slope which will transform the pressurized current into a gravitational current. At this stage there is a need for a ventilation system to guarantee that the current will pass through. After this stage, the tunnel has a diameter of 4 metres and a 1.3 1000 slope until the end. At the 22+570 km the maximum water density is 3 metres and its maximum speed has been calculated as 2.86 m/s. The tunnels discharge rate has been calculated as 27 cum/s. The tunnel must be capable of transferring 300 million cubic metres of water per year.