Tunnel lighting is about visual adaptation and traffic safety, not maximum brightness. Exterior luminance, speed, portal orientation and pavement determine entrance needs.
LED dimming supports weather, day-night and traffic stages, but sensing, circuits and fault strategy must be reliable.
Zone by visual adaptation
Entrance, transition, interior and exit zones perform different luminance tasks.
- Record exterior luminance and orientation
- Use speed to define transition
- Assess short tunnels by actual visibility
Evaluate luminance and uniformity
Pavement reflection affects what drivers see, so horizontal illuminance alone is insufficient.
- Confirm pavement material
- Control longitudinal and transverse uniformity
- Avoid repetitive bright-dark bands
Control glare and guidance
Positions, optics and repetition affect comfort and directional guidance.
- Limit high-angle brightness
- Maintain continuous guidance
- Check portals and curves
Stage dimming with safe fallback
Output should follow exterior light, time and traffic, with a safe state on sensor or communication failure.
- Use independent emergency circuits
- Keep local control
- Record levels and acceptance results
