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Abstract:
Highway Capacity Manuals (HCMs) typically estimate the highway capacity by considering various factors including the heavy vehicle (HV) ratio. HVs are generally believed to impact the highway performances negatively and HCMs reflect such impacts by using the daily average HV ratio for deterministically estimating the highway capacities. However, the breakdown flow rate that triggers the congestion does not always occur with the same demand levels and the deterministic approach needs to be carefully examined. Image detectors that are installed throughout the urban freeways in Seoul, Korea by the Seoul Civil Highway Management Center are used for collecting traffic data including volume, speed, occupancy, and vehicle type. Three study sections of urban freeways that are often prone to the bottleneck phenomena are chosen for the data collection. The data collected in September 2009 on typical weekdays that are free from unusual weather or accidents are used to test the appropriateness of using Korea Highway Capa
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