Dimming
Dimming means varying the light intensity that is emitted from the lights. It can be adapted in real time or programmed in advance.
Programmed dimming
Programmed dimming means that the light intensity is automatically varied according to the time of night. Based on a traffic study, LuWa has drawn up a strategy for varying the intensity of lighting.
The night-time dimming program is systematic and can be modified to different scenarios and days of the week on both motorways and trunk roads. From Sunday to Thursday inclusive, the lighting intensity is set at 70% from 10 p.m. until midnight and then at 50% between midnight and 6 a.m. On Fridays and Saturdays, the intensity is set at 85% from 10 p.m. until 11 p.m., at 70% from 11 p.m. until midnight and then at 50% between midnight and the point at which the lights are turned off.
In terms of the slip roads, if a vehicle is detected, the light intensity will automatically and instantly increase by 20% for a set period of time.
In order to save energy, the light intensity in any rest areas will only be varied when a vehicle and/or pedestrian is detected.
These dimming programmes have no longer been in use on central reservations on motorways since mid-September 2022 and on trunk roads since mid-December 2022 as a result of energy-saving decisions taken by the Walloon government in the aftermath of the energy crisis.
Real-time dimming
Real-time dimming is based on the detection of vehicles and is used in areas where maximum lighting is needed if a user is present since the areas are deemed to be more prone to accidents.
Dynamic dimming that uses presence detection is put in place on slip roads, which are less busy at night, at pedestrian crossings and in rest areas. It maintains a low level of lighting when nobody is present but then instantly increases it when a new user arrives.
Dynamic dimming can also be linked to a specific quantity of users via a traffic flow detection system. Dimming therefore makes it possible to lower the level of lighting if there is very little traffic on a road.
Finally, dynamic dimming can also be used within the context of specific events that need maximum lighting, such as roadworks, accidents or in exceptional weather conditions.