Document Details
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Document Type |
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Thesis |
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Document Title |
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AN INVESTIGATION OF THE EFFECTS OF SOME TRAFFIC PARAMETERS ON THE SATURATION FLOW RATE AT SIGNALIZED INTERSECTIONS IN MAKKAH ALMUKARRAMAH استقصاء تأثيرات بعض المتغيرات المرورية على معدل التشبع للتدفق عند تقاطعات الإشارات الضوئية في مكة المكرمة |
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Subject |
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Faculty of Engineering |
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Document Language |
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Arabic |
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Abstract |
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Highway Capacity Manual (HCM 2000) provides adjustment factors for addressing the impacts of operational factors on the standard value of saturation flow rate. Thus, an effective value of the saturation flow rate can be assessed at any intersection that does not meet the ideal condition. This dissertation mainly aims to investigate the saturation flow rate and estimate correspondingly effect of some traffic parameters on saturation flow rate at signalized intersections in Makkah, Saudi Arabia. The adjustment factors for U-turns, heavy vehicles, number of through lanes, and lane width were investigated. Data was collected at five non CBD signalized intersections using video cameras that mount on the nearest light pole of the studied approaches. The headway data were extracted from video tapes using video-editing software with an accuracy of 1/30 sec. Headways were grouped to different categories based on both vehicle types (passenger cars or heavy vehicles) and type of turning movement (left- or U-turning vehicles). Total duration of the study was 18.5 hours. Sample size includes 1589 and 1639 successive headways of U-turn and heavy vehicles studies respectively. Valid cycles were included in the analysis for the four selected studies, which include U-turns, heavy vehicles, number of through lanes, and lane width. They were 234, 327, 564, and 560 cycles respectively. In the total, 1015 left-turn vehicles and 574 U-turn vehicles were obtained. Also, 1277 passenger cars and 362 heavy vehicles were obtained. In the analysis of left-turning vehicle preceded by a left-turning vehicle in a left-turn lane, the average headway is found to be 1.90 seconds. When a U-turning vehicle preceded by a U-turning vehicle in a left-turn lane, the average headways is found to be 2.37 seconds. Analysis reveals that the larger the percentage of U-turning vehicles, the greater the effects of U-turns on the saturation flow rates. When a passenger car preceded by a passenger car in a through lane, the average headways is found to be 1.54 seconds. When a heavy vehicle preceded by a heavy vehicle in a through lane, the average headways is found to be 3.01 seconds. In addition, the study implies that the larger the percentage of heavy vehicles in the through lanes, the greater the effect of heavy vehicles on the saturation flow rates. Based on headway distributions for different cases of vehicular movements corresponding adjustment factors are estimated at different percentages of U-turns and heavy vehicles. The results show that the adjustment factors of both U-turning vehicles and heavy vehicles are similar to other studies in the USA. The adjustment factors for number of lanes for approaches having through lanes of 1, 2, and 3 are found to be 0.86, 0.93, and 0.95 respectively. The adjustment factors for lane widths with 3.3 m, 3.5 m, and 3.6 m are found to be 0.84, 0.97, and 1.0 respectively. The results indicate that the overall saturation flow rate increases with an increasing number of through lanes and lane width in the through lane group. In addition, the adjustment factors of number of lanes and lane width in the through lane group is low compared to those developed in the USA. The average headways estimated for all the four studied parameters, are low compared to those obtained in USA. It implies that the driver behavior in Saudi Arabia is more aggressive as compared to other countries. Also, the ideal saturation flow rate in Makkah (2500 pcphpl) is higher than that was suggested in HCM 2000 (1900 pcphpl). Investigating the driver's headway choice behavior it was observed that the mode of the headway distribution, rather than the mean, is a better representation of the central tendency particularly for the through lanes. The methodological approach presented in the thesis can be utilized to investigate other factors, which include area type based on land use, area population, right-turns, left-turns, and weather. It will also help in the preparation of Saudi Arabian Highway Capacity manual. The study outcomes can be utilized in the planning and design of traffic signals and geometric features of the roadways. The findings of the study will also be useful for the traffic simulation models to analyze microscopic characteristics of the traffic flow in Saudi Arabian conditions |
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Supervisor |
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dr.Hamed Omar Al-Bar |
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Thesis Type |
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Doctorate Thesis |
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Publishing Year |
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1431 AH
2010 AD |
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Added Date |
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Wednesday, July 28, 2010 |
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Researchers
| خالد عبد الرحمن أسره | Osra, Khalid Abdulrahman | Researcher | Doctorate | |
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