Converting the UK calculation of road traffic noise (CORTN) to a model capable of calculating LAeq,1h for the Tehran’s roads

This paper describes the methodology through which the UK calculation of road traffic noise (CORTN) has been converted to the algorithms that are able to calculate hourly A-weighted equivalent sound pressure level (LAeq,1h) for the Tehran’s roads. The methodology adopts two different approaches to model calibration and performance test through the holdout validation method on the basis of the database including 52 samples taken from 52 sampling stations located alongside 5 roads of Tehran at distances less than 4 m from the nearside carriageway edge. As to the CORTN manual the distances less than 4 m are considered to be equal to 4 m. In the first approach the model is calibrated through carrying out nonlinear regression parameter estimation using 50% of samples to replace the basic noise level parameters with the new ones that are presumably able to satisfy the objective of the study with an acceptable fitness of the model. In the second approach the model calibration is carried out on the basis of 30 measurements taken from 2 roads. In the next step the other subsets of samples are introduced into the calibrated equations to conduct the performance test. Non parametric goodness of fit tests, i.e. two related samples Wilcoxon and two independent samples Kolmogorov–Smirnov, respectively conducted for the calibration and the performance test steps; indicate satisfactory results for both approaches.