A city in Denmark will switch to red street lights along key roads to combat the impact of light pollution from artificial lighting on a colony of bats, while also trialling smart technology that could interact with cars.
Gladsaxe, located north-west of the Danish capital Copenhagen, has begun installing around 5000 red light-emitting diode (LED) street lights, including along the tree-lined Frederiksborgvej where seven species of bats have been found.
According to Daily Galaxy, the move from white to red lighting follows findings from the Danish Road Directorate (DRD) showing bats are disrupted by short-wavelength light, such as the white, blue and green wavelengths.
The switch to red LEDs introduces longer-wavelength light, which the DRD says has less impact on bats’ ability to use echolocation, as well as reduced impact on breeding and feeding behaviours.
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The red LEDs also provide sufficient lighting for road-user safety, while consuming less power than sodium vapour lights and requiring lower maintenance.
Their brightness can be adjusted if required, and the lights also incorporate motion-sensing technology.
As well as being less disruptive to bats and other wildlife, the red lighting is intended to remind residents and commuters of areas where vulnerable species live and navigate, helping to increase public awareness.
The Danish project is part-funded by the European Union’s ‘Lighting Metropolis – Green Mobility’ program, which spans cities in Denmark and neighbouring Sweden and has seen around 50,000 LEDs replace older streetlights.
In Australia, street lighting is more commonly white LED-based, replacing older sodium lights – with their more yellowish glow – as networks are renewed. Warm-white LEDs that can be dimmed to reduce light pollution are being trialled on the Bass Coast in Victoria.
The rollout of LEDs with smart capability in Europe could eventually see street lights interact with software-defined vehicles (SDVs) of the future.
“The streetlight has come of age. Think of not only providing quality lighting, but also as a digital node with its own IP address on a network that extends to every road and street in your city,” said Harry Verhaar, a spokesperson for Dutch company Signify, in a 2021 report on The Parliament.
“These streetlamps have the potential to house 5G and Wi-Fi connectivity, remote-controlled billboards, CCTV, and microphones capable of detecting sudden loud noises which can be quickly investigated,” said Mr Verhaar.
“Nodes and sensors can provide data-based insight into electricity usage, noise pollution, as well as traffic. The light’s brightness can also be controlled to adapt to nearby activity.”
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