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The vehicle time headways of arriving traffic flows at signalised intersections are examined in this study. Low traffic conditions are considered, and traffic lanes that carry less than 500 vehicles/h are studied. Data are obtained from 10 signalised intersections in Turkey. The lanes are classified with respect to movements of traffic flows. Seven distribution models are taken into account. The goodness of fits of the observations with the theoretical distribution models are evaluated using chi square (χ2) and the Kolmogorov–Smirnov tests. The results are considered with respect to both lane type and traffic volumes. The presented results show that log normal, Weibull, gamma or Pearson V distribution models can be used instead of the exponential distribution in modelling vehicle time headways.

The future traffic noise generation from Trans-European Motorways still under construction throughout Europe was analyzed in a study aimed to introduce standard noise control systems into the TEM Recommendations. Different prediction techniques developed by national institutions of nine countries were employed in computations of noise levels at 15 m from curbsides for varying traffic parameters. Comparisons between results relative to the procedures demonstrated that the USA method (FHWA) yielded about 5 dBA higher levels than European models especially in mountainous terrains and at higher percentages of heavy vehicles. Applying a statistical regression analysis, a simplified mathematical model for TEM noise predictions was developed with a satisfactory correlation coefficient. A new combined parameter, T(u,s,n,h,g), corresponding to interrelated TEM traffic variables (volume, speed, number of lanes, heavy vehicle percentage, and road gradient), affecting noise generation, was analytically defined and represented in the model. Reviewing the existing traffic noise criteria in the world and TEM countries, the prediction model was then improved to establish TEM noise standards taking into account environmental factors and was implemented for the required performances of the noise abatement measures applicable in every type of TEM. [Supported by Directorate of Turkish Highways within the TEM project coordinated by United Nations, Transport Division.]