Noise-reducing Motorway Overlay with Green Benefits 

FULL SHIELDING WITH SOLAR CELLS ON THE ROOF 

In Denmark, the number of homes with road traffic noise levels above the limit value of 58 dB on average has been calculated at 723,000 homes. This corresponds to 1.36 million citizens nationwide. In many places, 4-5 meter-high noise screens have been installed, but the screens only reduce the noise level for the heavily exposed homes very close to the highway, while homes up to a kilometer away still have a noise level above the noise limit value of 58 dB. 

A study published in 2021 conducted on 2 million Danes in the period from 2004 to 2017 shows that there is a link between road traffic noise above 55 dB and a number of diseases such as cardiovascular disease, breast cancer, blood clots and dementia. In a 2018 report, the WHO has also pointed out that the health consequences of living in noise are even worse than previously thought. WHO recommends that the noise limit should be further reduced from 58 dB to 53 dB for health reasons. 

Through Hedehusene in Høje-Taastrup Municipality, 4 m high noise barriers have been erected along the Holbæk highway – yet more than 1,500 addresses are exposed to traffic noise from the highway above the 58 dB limit. Similarly, there are 4,500 addresses in Hvidovre along the Amager highway. The municipalities therefore wanted to investigate the effect of a fully shielding construction with solar cells on the roof above the highway, which SYSTRA helped with. 

LOWER NOISE LEVELS WITH GREEN BENEFITS 

The study had the following main objectives: 

• Technical and architectural account of possible covers 
• Description of the technical construction and roughly estimated construction costs 
• The expected reduction in noise level 
• Description of the derived positive effects and consequences for the surrounding urban environment 
• Examination of the formal process for the establishment and approval of the cover in collaboration with Høje-Taastrup and relevant authorities and stakeholders 
• Estimated calculations of any solar energy system – establishment, operation, profitability 

The study shows that a 2.1 km cover through Hedehusene and Fløng can reduce the number of noise-affected homes from 1862 to 355 – a reduction of approx. 1500 homes. The solar cells on the roof of the canopy could generate 11 MW of green energy, which corresponds to the annual energy consumption of 1,375 households. 

The results of the study speak for themselves: We should work with lower noise limits and more effective measures. The shielding and other measures that we typically have along highways today do not provide a sufficient reduction in noise. Fortunately, the problem can be addressed, and the study shows that it is even possible to use a shielding structure to collect green energy. 

Rune Rasmussen, Project Manager

If you would like more information about the study, please contact Rune Rasmussen at [email protected]

Read more about covering the Amager motorway in this report: Covering the Amager motorway in Hvidovre Municipality