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Description
Noise barriers are widely used to reduce road traffic noise, yet the relationship between calculated noise reduction and residents’ perceived benefit remains unclear. This paper presents a before/after evaluation of a noise barrier project comprising approx. 8 km of 6–9 m high barriers along the E45 (North Jutland Motorway) in Aalborg, affecting more than 2,000 dwellings. The evaluation combines noise calculations at dwellings (Lden), questionnaires collected before and after construction, and qualitative interviews with selected respondents. The results indicate an average noise reduction across all dwellings of approximately 4–5 dB. The most noise-exposed dwellings, with façade noise levels above 68 dB, experienced the largest effect, with average reductions of up to 9–12 dB. Survey results show, among other findings, that the share of respondents who are highly annoyed decreases from ~60% to ~42%, and the share considering the noise level unacceptable decreases from 57% to 38%. The barrier nonetheless divides local opinion: approx. 23% of residents report liking the barrier, while 30% report disliking it. A positive association is observed between calculated and perceived noise reduction, but the effect size appears small, suggesting that multiple factors beyond decibel reduction shape residents’ experience. One likely contributor is overly high expectations from residents. The expected noise reduction before the project averaged 6.8 on a 1–10 scale, whereas the perceived reduction after the project averaged 2.5 – underscoring the importance of clear communication about anticipated outcomes.