Why is tunnel lighting important?

Answer

The transition from open roads to tunnels causes a transition in illuminance circumstances, in particular in the daytime. It is important to realize a gradual transition at the entrance and exit of a tunnel; the human eye needs several seconds to adjust to the change of situation. If the illuminance transition is too abrupt, road users are unable to discern details for a few seconds and that may be enough to distract them (see the archived factsheet The road safety of motorway tunnels).

Part of fact sheet

Public lighting and vehicle lighting

Visual information is of the utmost importance to road users.

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