Red LED streetlights make UK road bat-friendly

“Research shows some species of bat are light shy and will not cross roads lit by white lights, which can stop them accessing food supplies and water,” according to the council. “Bright street lights also attract the flies and insects the bats feed on, and so reduce the food available for bats and other mammals in their typical feeding areas.”

The Council’s information refers to a “unique recipe of light”, without offering details, and also refers to a similar lighting project in the Netherlands.

One recent Netherland’s project is at Nieuwkoop and was developed with Philips Lighting (now re-named Signify) and uses Philips’ ClearField spectrum, which sadly the firm does not publish. However, the installation at Nieuwkoop was based on bat research by the University of Wageningen and Philips (Response of bats to light with different spectra: light-shy and agile bat presence is affected by white and green, but not red light) which compared the response of the animals to white, green and red street lighting – the latter using ~630nm (‘high-efficiency red’ or orange-red) LEDs.

The Nieuwkoop lights designed to “ensure bats can enjoy the night time as if there was no artificial lighting in place, while ensuring good visibility for residents living in the area. Therefore no compromise was made on safety”, according to Philips.

This Worcestershire bat-safe light project, a collaboration the Council and Jacobs, was initiated after a pedestrian road crossing needed to be installed near Warndon Villages on an otherwise un-lit stretch of road.

“The lighting scheme is being installed in two phases of work, to ensure the safety of road users,” said the Council. “Phase one is now live at the exit from Plantation Drive Roundabout. Phase two [expected late September] will see the full switch on of the controlled crossing and the new, extended carriageway lighting.” It describes the resulting installation as “fully compliant with the required standards”.

‘Batlamp’ is another bat-friendly lighting product from the Netherlands, first used at the end of 2011 on the A74 motorway at Tegelen, and subsequently used on multiple Netherlands projects. Illumus’ version operates at 592-594nm – at least one other of its incarnations is a monochromatic 610nm streetlamp.