HEPER TUNNEL LIGHTING: SABUNCUBELI TUNNEL, TURKEY

The Sabuncubeli Tunnel, a vital twin-tube roadway linking the cities of Manisa and İzmir in Turkey, now benefits from a full tunnel lighting upgrade. As CU Phosco’s exclusive tunnel and amenity lighting partner for the UK and Ireland, Heper brings extensive international experience and product innovation to safety-critical infrastructure projects around the world.

Commissioned by the General Directorate of Highways in Turkey, this project involved the design and delivery of a complete tunnel lighting system for the 4,070m-long dual-bore tunnel. The route had previously been notorious for its 14 sharp bends, heavy winter ice, and steep 9.5% gradients. Since opening in 2018, the tunnel has transformed local travel, reducing the Manisa–İzmir journey to just 15 minutes and improving conditions for nearly 40,000 vehicles per day.

Constructed using the New Austrian Tunnelling Method (NATM), the Sabuncubeli Tunnel posed a range of safety and operational challenges – from high traffic speeds to changing light conditions and 24/7 usage.

These were addressed using the GOLEDO tunnel lighting system, designed in accordance with 2004/54/EC, CIE 88:2004, EN 13201 and other relevant international standards. The lighting concept featured:

• Precision Zoning: The tunnel was segmented into approach, threshold, transition, interior and night-time zones – each carefully engineered for optimal luminance and uniformity.
• Dynamic Control: Dual luminance meters were installed at the tunnel portal to adapt brightness levels in real time based on ambient conditions, maximising efficiency while maintaining visibility.
• Optical Performance: Counter-beam optics were applied in the threshold zone to minimise glare, with symmetrical optics used in the interior zone to maintain visual comfort and safety.
• Robust Design: The lighting system included IP66-rated stainless steel housings with excellent ingress protection and resistance to harsh tunnel conditions, including vehicle exhaust and high humidity.

The GOLEDO tunnel lighting system significantly improves driver safety by supporting visibility and reaction times, particularly at high speeds. The adaptive design ensures safe light transitions, preventing sudden changes that can cause driver disorientation. High-efficacy luminaires (above 120 lm/W) combined with dimmable drivers and dynamic control ensure optimal energy performance and cost-efficiency.

The modular installation also ensures long-term reliability with minimal maintenance – a key consideration in tunnel environments where access is restricted and closures are costly.

This project stands as a prime reference for how a partnership approach can support international best practice in tunnel lighting – combining optical precision, engineering resilience, and energy efficiency to deliver a safe and sustainable lighting system.

This reference showcases HEPER’s long-standing expertise in tunnel lighting, serving as a foundation for future joint developments between HEPER and CU Phosco in the UK and Ireland. As HEPER continues to strengthen its tunnel lighting portfolio, this project acts as a key benchmark ahead of upcoming joint projects to be developed and delivered in collaboration with CU Phosco.