Comparative Analysis of Peak Hour Factors for Four Major Collector Roads in Sulaymaniyah City, Iraq

Volume 13 ,Issue 1 ,December 2026 ,Pages 10-26

Authors

Laveen Kawa Burhan Alden 1 ; Chro Haidar Ahmed 1

1 Civil Engineering Department, College of Engineering, University of Sulaimani , KR, Iraq

DOI logo 10.17656/sjes.10229

Keywords

Abstract

This study presents a comparative analysis of Peak Hour Factors (PHF) for four major collector roads in Sulaymaniyah City, Iraq. Traffic volume data were collected using video recording techniques and processed at 15-minute intervals over a 24-hour period. The Peak Hour Factor was calculated for each site to assess the uniformity of traffic demand during peak periods. The results reveal notable variations in PHF values among the selected roads, indicating differences in within an hour demand concentration that were not directly proportional to peak-hour traffic volume. PHF values ranged from 0.849 to 0.986, with both extremes recorded at Twimalik during the morning period in opposite directions of travel: inbound direction showed the greatest within-hour concentration, while outbound direction showed the most even within-hour distribution. Kaniba exhibited consistently high PHF values (0.924–0.969) despite carrying the largest peak-hour volumes (up to 1,807 veh/h per direction). The lowest PHF coincided with the lowest observed volume, indicating that a low PHF does not necessarily correspond to a high hourly traffic demand. The largest differences occurred between the two directions of the same corridor rather than between corridors, with Twimalik ranging from 0.849 to 0.986 across its four directional observations. The observed PHF values were generally within ranges reported in comparable studies, although such comparisons are used only as contextual references rather than as classifications of traffic performance. The findings provide a descriptive basis for identifying periods and directions with greater within-hour demand concentration and for guiding future detailed operational investigations. Because PHF enters capacity analysis as a demand adjustment factor (v = V/PHF), the reported values also indicate the extent to which the design flow rate exceeds the average hourly volume at each site. The study contributes the first documented directional 15-minute traffic dataset covering a full 24-hour period for these corridors, providing a quantitative baseline for future surveys and identifying the periods and directions in which detailed operational investigation would be most productive. Because the data were collected on a single weekday during the summer holiday period, the values reported characterize the survey day.

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