Seven Hills Seven Tunnels (Yedi Tepe Yedi Tünel) 


Project name

Seven Hills Seven Tunnels Project

Project Location



The Istanbul Metropolitan Municipality


KİS-MAK Ordinary Partnership

Start and End Date

2006 - 2008


Total Concrete Amount 405.000 m³ Concrete Classes Shotcrete 420 123.000 m³, C 25/30 and C 30/37 Gross concrete 282.000 m³


Projected to be used for the next millennium, the “Seven Hills Seven Tunnels” project has been designed to ease Istanbul’s intense traffic. OYAK Concrete has supplied all of the ready-mixed concrete used so far. As part of this project, following tunnels have been built:

 Tunnel 1: The Piyalepaşa – Kağıthane Tunnel, 3,023 m in length. Vehicles enter the tunnel at Kasımpaşa – Piyalepaşa, pass under the Okmeydanı – Çağlayan district and exit at Kağıthane, connecting to TEM through Sütlüce Connection Road.

 Tunnel 2: Dolmabahçe–Bomonti Tunnel, 4,091 m in length. The route starts with the tunnel entrance at Kadırga, which is located on the northern side of İnönü Stadium, passes under Taksim bypassing Taksim – Kabataş–Karaköy traffic, and goes under the Feriköy district, ending with the Kasımpaşa (Bomonti) Piyalepaşa exit and connecting to the E-5.

Tunnel specifications:

The tunnels have been built using earthquake-proof methods. The project was planned to enable the tunnels to be used as a sanctuary, hospital, and transportation road in the event of a disaster. Fans measure carbon monoxide levels and start operating automatically when the ventilation rate falls below 8 km/h. There is a surveillance camera once every 100 m. Emergency exits are placed every 250 m. All equipment within the tunnel can withstand a temperature of 250°C for two hours. Temperature changes are measured with receivers. Corrosion-resistant and heat-proof special concrete is used instead of asphalt by adopting a different technology, as the toxic gases given off by asphalt could pose a danger in case of a fire. This application is a first in this field, and for the first time in Turkey ready-mixed concrete has been used in a tunnel pavement instead of asphalt.

Human Resources

OYAK Cement’s human resources management mentality consists of the adoption of approaches and applications that support strategical targets and performance, while responding to the special needs of the different industries with which it conducts its activities in an appropriate and efficient manner.