CHARACTERIZATION OF PEAK HOUR TRAFFIC

Abstract

The I-Iighway Capacity Manual (HCM) suggests a design value of 0.92 for congested urban areas and 0.88 for rural areas, incase no field measurements are available. These default values give general guidelines, but they might be too coarse for practical usage. An effort is made to model the actual peak-hour factors as a function of volume-to-capacity ratio and the functional classification of roads. A total of 61 data points were obtained, 41 for Arterial and 20 for Sub-arterial road sections, for analysis. The results show that, among several functional forms, the simple quadratic function established with functional classification of roadways can be used to predict N-IF 1511when the value of v/c ratio is given at a given road section. The importance of the traffic composition is shown by using relationships developed between PHFl5jnjfl and traffic composition on different road sections. Statistical comparison is used to show that volume to capacity (v/c) ratio is more dependable than traffic volume for prediction of PHF15minvalues. Comparing to the models given in literature, the proposed model gives predicted PHFI5rnjn values closer to the observed PHF15',in values varying between -4.6% and +3.3% on the arterial road sections and between ± 8.7% on the sub-arterial road sections.