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German city goes batty for LED-lit recreational trail

Tunnel vision: Before seeing its LED-lit railway recreational trail to fruition, Wuppertal had to come up with a plan to protect endangered bats, which prefer their tunnels dark.

ROME – At the European Commission’s conference here today on LED lighting for smart cities, one thing became clear: Any public outdoor LED scheme is bound to run into unique challenges.

No city summed that up better than Wuppertal, Germany, which was keen to convert a 22-kilometre stretch of disused railway into an LED-lit day-and-night recreational trail which cyclists and walkers could travel through abandoned tunnels, over aqueducts and along the old trackway.

There was one main problem: Bats. European law protects the endangered winged mammals; they lived in the route’s tunnels; and, in a potential deal stopper, they don’t like light. The bats were there first, so they were going to win the battle, lest Wuppertal figured out how to accommodate them.

‘It was a severe conflict,’ recalled city director and treasurer Johannes Slawig, speaking during a morning ‘lessons learned’ panel. ‘We had to find a situation in which the people and the bats could live together.’

Wuppertal’s answer? It took advantage of the directional nature of LED lighting, mounting luminaires four metres high pointing down, which left 4 dark metres at the top of the tunnel for the bats. Conventional lighting would have sprayed light above, disturbing the bats.

A digital control system which the city uses to remotely adjust lighting as conditions require has also helped maintain optimal conditions for the cave dwellers.

Simply put, ‘it works,’ said Slawig. Wuppertal, the birthplace of aspirin and Friedrich Engels, and a city of about 350,000 located near Cologne and Düsseldorf, will officially open the line on Dec. 7.

‘It combines the recreation of people with the protection of nature, with the protection of bats in this situation,’ said Slawig. ‘That is possible because of the special management of the lighting system, which is able to light in each situation we need – summer, winter, protection time of bats, days with sunny weather, days without sunny weather.’

Wuppertal is funding the €2 million scheme through an award it won in a competition sponsored by the German government.

The city was just one of several to present here during the second day of the EC’s ICT Key Enabling Technologies Conference. Today focused exclusively on the deployment of LED lighting for sustainable smart cities, for which the EC hopes to provide funds for multi-city projects. Cities including Milan, Eindhoven, Albertslund (Denmark) and regions including Sweden’s Skåne shared insights on challenges ranging from financing to data security to collaboration. Watch for more reports from Lux.

Photo is from C. Robiller / via Wikimedia