top of page


The ILLIOS measures the level of illuminance within the tunnel bore to ensure interior illumination levels are being continuously maintained, in order to affect safe lighting conditions for drivers. Illuminance, or incident lighting, determines the amount of light that covers a specific surface or area within the tunnel.


  • Accurate measurement of illuminance within the tunnel bore

  • Silicon photo diode, Vλ filtered to provide a spectral response close to that of the average human eye

  • IP65 / NEMA 4X rated external enclosure

  • Operating temperature of -30 °C to +70 °C to ensure stable readings across all prevailing ambient temperature conditions

  • Self contained intelligent analyser for direct connection to host controller

  • Supplied complete with PC based utility software for set-up and control of the instrument



  • Designed specifically for monitoring in tunnels

  • Rugged design to withstand corrosive atmospheres and regular tunnel washing

  • Simple installation and mounting

  • No moving parts and low maintenance requirements

  • Flexible integration options

bottom of page