The T4 tunnel required the integration of all subsystems into a single SCADA platform, ensuring continuous operation, high safety levels, and full compatibility with the existing control centers in Leptokarya and Moschohori.

The new infrastructure enables:

• Real-time monitoring and control of all tunnel systems.
• Faster incident response and automatic safety scenario activation.
• Improved energy efficiency through optimized control of lighting and ventilation.
• Unified operation with the PATHE tunnel network, ensuring centralized supervision from both control centers.

The T4 tunnel upgrade is another milestone where AS HELLAS, leveraging its expertise in Industrial Automation for critical infrastructure, contributed to the modernization of national assets with technology, reliability, and safety.

AS HELLAS, in collaboration with SIEMENS S.A., undertook the design, implementation and commissioning of the SCADA system for the Katerini T4 Tunnel, as part of its overall modernization.
Managed by Aegean Motorway S.A., the tunnel reopened to traffic fully upgraded, meeting the latest European standards in road safety, energy efficiency, and digital operations.

The Project

The 1.1 km long T4 tunnel is a critical part of the northern PATHE highway, serving thousands of vehicles daily.
The main challenge was to unify and automate all control systems (lighting, ventilation, fire detection, communication, and other subsystems) in full compliance with European tunnel safety standards.
The new automation platform had to guarantee uninterrupted operation, precise control, and simplified maintenance — all without disrupting the operation of the integrated tunnel network (T1–T2–T3).

AS HELLAS Solution

AS HELLAS designed, developed, and commissioned a fully integrated SCADA system that connects all T4 subsystems and communicates seamlessly with the control centers.
The solution was based on Siemens WinCC OA and S7-400H PLCs, utilizing OPC UA, Modbus TCP, and SNMP protocols for unified communication with the field equipment.

The scope included:

• Design and programming of PLCs and RIOs with redundant architecture.
• Development of new software for lighting, ventilation, traffic management, CCTV, ERT, and tunnel power distribution control.
• Integration of the T4 SCADA with existing systems of tunnels T1–T2–T3, maintaining full DRS (Disaster Recovery System) functionality.
• Internal simulations and full on-site commissioning (SIT).
• Additional services including overpressure control logic enhancements and simulation of bidirectional/unidirectional scenarios.