ITU‐T's Technical Reports and Specifications 397 Figure 5 – Example of utility tunnel lighting [Source: Abu Dhabi Utility Corridors Design Manual, b‐1] Lighting should be designed to maintain a minimum light level of 150 LUX at the walk surface and be fitted with motion detectors and any necessary overrides for safety purposes. NOTE – Different countries may have other national standards or regulations. Figure 6 – Example of utility tunnel fire detection/sprinkler system [Source: Abu Dhabi Utility Corridors Design Manual, b‐1]