EURASIA TUNNEL
The subsea highway link between Europe and Asia
The Eurasia Tunnel crosses the Bosphorus Strait parallel to the Marmaray railway tunnel, providing a direct, high-capacity link between the Asian and European sides of Istanbul.FS Engineering, operating in a joint venture with Altinok Consulting Engineering, was awarded the contract for construction supervision and independent design review for the Eurasia Tunnel project. The infrastructure asset extends for a total route length of 14.6 km, connecting the Asian district of Göztepe with the European district of Kazlıçeşme. The alignment runs subsea beneath the Bosphorus for approximately 5 km, of which 3.4 km comprises a bored tunnel reaching a maximum depth of circa 106 m below sea level.
The tunnel structure is configured across two decks providing two running lanes in each direction. It has been designed to accommodate a dft (design flow traffic) of up to 100,000 vehicles per day, successfully reducing cross-strait transit times from 1 hour 40 minutes to just 15 minutes.
| THE PROJECT IS DIVIDED INTO 3 MAIN SCOPES OF WORK |
PART 1 – EUROPEAN HISTORIC QUARTER SECTION (5.4 km alignment): This scope comprises carriageway widening and asset renewals across the existing primary and secondary highway networks. Deliverables include the construction of grade-separated junctions, flyovers, and dedicated highway and pedestrian underpasses. PART 2 – BOSPHORUS STRAIT SUBSEA CROSSING (c. 3,340 m tunnel): This section comprises a bored tunnel passing beneath the Bosphorus, excavated utilizing a 13.71 m large-diameter Earth Pressure Balance / Slurry TBM. The alignment reaches a maximum depth of 106 m below Ordnance Datum (sea level). Due to extreme hydrostatic pressures at the tunnel face (11 bar), highly heterogeneous ground conditions, and zones of high permeability, the project represents an unprecedented and highly complex engineering feat. The scope also features the Concessionaire’s Operations and Control Centre (OCC). This facility houses a 24/7 control room, utilizing an integrated SCADA (Supervisory Control and Data Acquisition) system to capture real-time telemetry for comprehensive traffic management, asset monitoring, and incident response across the network. PART 3 – ASIAN SECTION (3.8 km alignment): This scope covers the tie-in of the new highway alignment with the existing D100 corridor, establishing a direct link between the Göztepe district and the Istanbul–Ankara motorway. |
During the contract period, the FS Engineering–Altınok Joint Venture carried out project management, independent design verification of the detailed design, project planning and controls, contract administration and reporting, construction supervision, as well as the supervision of geotechnical and E&M (electrical and mechanical) activities. The mandate also included the supervision of the tunnel’s operation and maintenance.
The works were completed eight months ahead of the contract schedule and the contract was finalized in 2021, confirming FS Engineering’s role as a leading partner in the delivery and supervision of complex and strategic infrastructure projects on an international scale.
