Straylight from the windscreen - e.g. by dirt or reflection from the dashboard- like straylight from the eye or the atmosphere, causes a luminous veil that especially reduces the visibility of details in relatively dark scenes like tunnel entrances. This phenomenon therefore influences the required light level in the tunnel entrance. Details are given on the angular dependency of the scattered light and given on the various components of the stray light, which enables generalization to other circumstances. See for part I and II PB 27787 and PB 27788
Abstract