TunneLseq is an advanced engineering software developed to automate tunnel entrance lighting calculations based on the Lseq (Equivalent Veiling Luminance) approach, in accordance with the tunnel lighting guides published by the International Commission on Illumination. The system analyzes the visual environment of tunnel entrances and determines the threshold zone road surface luminance (Lth) in compliance with the calculation methods defined in the CIE 88 guide.

The fundamental concept of TunneLseq is to implement the Lseq-based perceived contrast method described in CIE 88 – Guide for the Lighting of Road Tunnels and Underpasses without requiring advanced lighting expertise, mathematical calculations, or the use of complex formulas from the user.

During the image scanning process, the user marks environmental components such as vegetation, sky, buildings, snow, roadway, tunnel portal, concrete surfaces, and similar elements without being constrained by a predefined diagram or fixed template. TunneLseq automatically classifies these areas using AI-based image processing algorithms and determines the percentage contribution of each surface within the driver’s field of view with high accuracy.

In the background, the software automatically applies the polar diagram approach defined in the CIE guides. The driver’s field of view is subdivided into 108 discrete regions, and the area percentages obtained from the scanned image are mathematically mapped to these regions. During this process, the user is not required to perform:

• Area percentage calculations,
• The corresponding area brightness level (kcd/m²),
• Formula input or verification.

As a result, TunneLseq:

• Does not require advanced lighting engineering knowledge or technical background,
• Does not expect users to perform mathematical calculations,
• Keeps complex and detailed formulas entirely out of the user interface,
• Implements the CIE-defined methodology in a transparent yet user-friendly manner.

Based on the scanned visual data, the Lseq value is calculated automatically and correlated with the minimum perceived contrast criteria defined in the CIE guides to obtain the Lth result. Depending on field conditions and image quality, the entire process can be completed within approximately 5 minutes.

Contribution to Multi-Stakeholder Project Processes

This approach not only simplifies the technical calculation process but also provides significant advantages for tender preparation and project management.

• Contractors can use TunneLseq to determine tunnel entrance Lth values quickly and reliably, facilitating the preparation of tender documents.
• Clients and road authorities can define reference Lth values in advance in accordance with the CIE guides and require all suppliers to design their solutions based on this single predefined criterion.
• This ensures that lighting fixture manufacturers operate under identical photometric conditions, making proposed designs directly comparable and verifiable.
• Differences arising from interpretation, methodological variation, or subjective assumptions are largely eliminated.

As a result, TunneLseq transforms tunnel entrance lighting:

• From a process overly dependent on individual designer interpretation,
• Into a common technical reference based on CIE guidance,
• Providing technical transparency and a fair evaluation framework in tender processes.