Leuven tackles night noise with ‘smart nudging’

The City of Leuven in Belgium is trying to strike the balance between a vibrant nightlife and people getting a good night’s sleep.

A trial project used sound monitors to map night-time noise levels, along with behavioural ‘nudges’ to reduce noise.

The nudges included adapting public lighting in response to noise levels, and using signage and light projections. The projections, for example, cut sound peaks by 30 percent, the city said.

The pilot was carried out along the Naamsestraat and the city is now looking at whether it can use the insights gained in other streets and neighbourhoods that are noisy at night.

Thomas Van Oppens, Alderman of ICT and Student Affairs for the City of Leuven, said: “Leuven is traditionally a real nightlife city. That’s nice, of course, but it also brings night noise and that is disturbing to say the least for those who have to show up at work fresh and cheerful the next day.”

Noise insights

The trial ran between August 2021 and November 2022. The seven noise sensors did not record anything but analysed noises of 70 decibels or more between 11 pm and 5 am. The analysis showed that Wednesdays, Thursdays and Fridays were especially noisy.

The noisiest month was October 2022 followed by March 2022, when COVID-19 measures were lifted.

The city also investigated the sources of night noise, finding that vehicles caused the most noise, followed by ‘residual’ noise that couldn’t be automatically categorised, then shouts or chants.

Van Oppens said: “Measuring is knowing and that is also the motto here. These results are extremely valuable. They teach us on which days of the week and at what times our nudging actions can have the most effect. This allows us to intervene in a very targeted manner.”

Nudging

One nudge saw lights dimmed or brightened for 10 minutes when the sound monitors registered night sounds that exceeded the 70 decibel limit for more than two seconds and were recognised as coming from people. This test ran from May to November 2022.

The city also experimented with a moving light projection which made it clear to people that they were leaving the party zone and entering the quiet zone. It asked passers-by to take the sleeping residents into account. Floor stickers and window signs carried similar messaging.

“This way you create more understanding and therefore more behavioural change,” said Van Oppens.

In the test period – three weeks during the summer holidays, and in October and November – the number of noise peaks decreased by 30 percent.

“That’s pretty spectacular,” said Van Oppens, adding that effect of the projection tapered off after around 1am.

The stickers and window signs worked less well, the research found.

“From this test project we can conclude that we can detect night noise without anyone reporting it,” Van Oppens said. “But more importantly: we can reduce night noise without the police having to intervene.”

The city plans to further experiment with measuring noise and nudging.