SYSTRA wins major tunnel project in Türkiye

SYSTRA Türkiye will design the Dörtyol–Hassa motorway and rail tunnel, in collaboration with the global engineering and consultancy group TYLin and commissioned by the Doğuş–Eze joint venture under the authority of AYGM, the body responsible for infrastructure investment.

The longest road tunnel in Türkiyé

The scheme will create a new transport corridor through the region, with two dual-lane highway tunnels and a single-line railway tunnel to strengthen regional connections.

The dual-lane road tunnel will be the longest in Türkiye and among the top five longest road tunnels in the world. Beneath the surface, the ground presents an extreme mix of problematic geological conditions, with a maximum overburden* of 1,600 metres – exceptionally high for this infrastructure. To meet this, the project combines tunnel boring machines with conventional excavation (NATM**).

*The total depth of soil and/or rock overlying the tunnel crown
**New Austrian Tunnelling Method: employs sophisticated monitoring to optimise various wall reinforcement techniques based on the type of rock encountered as tunnelling progresses.

The Dörtyol–Hassa project is a landmark in connectivity, creating a strategic multimodal corridor for the region. Its ambition is matched by its complexity, with extreme geology and unprecedented tunnel depths demanding innovative engineering and close collaboration. It is both a major opportunity and a formidable technical challenge.

Business Development Director, SYSTRA Türkiye

Ensuring safety and operational reliability

The greatest test lies in the tectonic environment. The alignment crosses the active Hassa–Kırıkhan segment of the East Anatolian Fault Zone, a major continental fault. The area has very high seismicity, with earthquakes of magnitude 7.3 recorded close by. These conditions demand cutting‑edge geotechnical design for long‑term safety.

To meet these stringent requirements and the expectations of this landmark project, SYSTRA’s teams will need to implement innovative techniques.