ROAD TRAFFIC NOISE IN NIGERIA: MEASUREMENTS, ANALYSIS AND EVALUATION OF NUISANCE

The investigation comprised field measurements of road traffic noise at over 60 sites in 8 cities in South-Eastern Nigeria and psychological survey, by questionnaires, of respondents living and working close to the sites. Instantaneous and 24 h noise measurements were made at the noisiest points, near the facades, of the houses of more than 150 respondents in the neighbourhood of each site. Several noise descriptors were either measured or calculated. Measured values ofLmax were as high as 105 dB (A) while residents were exposed to instantaneous levels of road traffic noise as high as 110 dB (A). Values of Leqand Ldnwere 84·6 and 68·0 dB (A), respectively, and sometimes higher in some of the sites. The calculated L10correlated positively with field data with a correlation coefficient of 0·8551. It was found that the measuredL10 was always higher than the calculated L10by about 4·5–8·8 dB (A) probably because of the reckless use of horn by motorists and reflection from the hills and trees. The type of house lived in, the disturbance of various activities by road traffic noise and neighbourhood noises which were most annoying to residents, were found to strongly affect the percentage of responses obtained with respective correlation coefficients of 0·9925, 0·9714 and 0·7237. The usual poor correlation, ranging from 0·3 to 0·4, between dissatisfaction response and noise exposure were obtained in this investigation. There appeared to be an income bias with respect to community response to road traffic noise, with low-income neighbourhoods reporting less annoyance and disruption of various activities by road traffic noise, and some evidence of adaptation to road traffic noise by residents of busy cities in South-Eastern Nigeria.