The modification of the UK CRTN (Calculation of Road Traffic Noise) formulae for the prediction of traffic noise from uninterrupted traffic flows has been researched. The report details the methods used for data collection of noise and traffic relationships, shows the shortcomings of the CRTN model in the New ZEaland situation, and shows how pavement type and chiseal texture as well as the ratio of medium to heavy trucks affect the level of traffic noise.
Full equations are provided that can predict the L10 traffic noise level from uninterrupted traffic flows to a tolerance of 2 dB(A) 95% of the time. The 1-hour L10 value can be obtained by adding 13 dB(A) to the 18-hour modified CRTN formula.
Details are provided on the effects of ground cover, facade reflection, and variance in noise-traffic relationships over a number of days. A guide to predicting traffic noise using the modified CRTN formulae is appended.
Keywords: Modelling, New Zealand, noise, prediction, roughness, traffic, traffic flow, uninterrupted flow