THE LONG-TERM EFFECT OF NOISE PROTECTION BARRIERS ON THE ANNOYANCE RESPONSE OF RESIDENTS

Results are presented of two parallel acoustic and psychological surve ys at four different barriers with four adjacent research areas and 12 experimental sites, and one untreated control area with two sites, in the outskirts of the cities Dusseldorf, Wuppertal, Krefeld and Neuss in 1976 and 1988. Conclusions from the results can be briefly summariz ed as follows. (i) There is not a simple causal relation between noise level reduction and annoyance reduction. (ii) Barriers produce high a nnoyance reduction at near sites but only minimal effects beyond 150 m from the highway. (iii) Annoyance reduction, on average, is relativel y greater than noise level reduction. (iv) Changing traffic volume on urban roads has stronger psychological effects than those of barriers. (v) Highway noise produces higher annoyance reactions than urban road traffic noise of the same level. (vi) After barrier construction the noise level influence on annoyance is weaker than before construction. (vii) A negative experience of residents before barrier construction is not likely to be influenced by the reduced immission level after co nstruction. (C) 1995 Academic Press Limited