The Kallidromo Tunnel stands as the crowning achievement of the Greek railway network and the longest railway tunnel in the Balkans. As the centerpiece of the new Tithorea – Lianokladi – Domokos high-speed line, this subterranean passage is the primary catalyst for the modernization of the Athens – Thessaloniki axis. By bypassing the old, arduous mountain crossings, the tunnel facilitates high-speed travel, effectively reducing the total journey time between Greece’s two largest cities by a full hour.
NAMA played a pivotal role in the design and construction supervision of the remaining tunnel structure, providing the technical certainty required to complete one of the most geologically complex infrastructure projects in Southeast Europe.
Technical Precision and Advanced Tunnelling Methods
Completing a twin-bore tunnel through the challenging geological formations of the Kallidromo massif required a sophisticated engineering approach and constant real-time evaluation:
- Twin-Bore Infrastructure: The project features two independent branches (one direction per branch), each with a cross-section of 65 m^2. NAMA was responsible for the final detailed design and supervision of the remaining 6 km of drilling for each branch, totaling 12 km of advanced underground works.
- The NATM Approach: The remaining sections were excavated using the New Austrian Tunnelling Method (NATM). NAMA’s design focused on sequential excavation and optimized primary support, allowing the tunnel to adapt to the varying rock mass conditions encountered deep within the mountain.
- Design Evaluation and Verification: A critical part of NAMA’s mission involved the rigorous check and evaluation of existing studies. Our team performed the final detailed design for the remaining part, ensuring that the structural solutions met modern high-speed railway standards and safety requirements.
- Supervision and Adaptive Engineering: Beyond the drawing board, NAMA participated in the on-site construction supervision. We were responsible for ensuring the precise application of the detailed studies and managing real-time modifications to address unpredictable geological situations, ensuring the project stayed on track despite the mountain's complexity.
Key Figures and Strategic Impact
The completion of the Kallidromo Tunnel marks a new era for Greek transport, aligning the country’s rail infrastructure with European high-speed standards:
- Balkan Record-Breaker: With a total length of approximately 9.03 km, it is the longest railway tunnel in Greece and the entire Balkan Peninsula.
- Time-Saving Efficiency: The tunnel is the key element in the Tithorea – Lianokladi – Domokos section, which allows trains to reach speeds of up to $200 km/h$, slashing the Athens – Thessaloniki trip by 60 minutes.
- Geotechnical Complexity: The project’s success hinged on the expert evaluation of highly variable geological conditions. NAMA’s geotechnical expertise was critical in navigating the complex fault zones and water-bearing strata of the Kallidromo range.
- Sustainable Logistics: By enhancing the capacity and speed of the rail network, the tunnel promotes a shift from road to rail, significantly reducing the carbon footprint of national logistics and passenger travel.
For NAMA, the Kallidromo Tunnel project demonstrates our ability to lead the supervision and design of "mega-projects." By managing the intricate balance between theoretical design and the unpredictable realities of heavy construction, we helped deliver a vital artery that connects northern and southern Greece more efficiently than ever before.
