Abstract
Passenger Car Equivalent (PCE) is essential for transportation engineering to assess heavy vehicles’ (HV) impact on highway operations and capacity planning. Highway Capacity Manual 2010 (HCM 2010) used PCE values and percent of heavy vehicles to account the impacts on both highway planning and operation, however, PCE values in the latest version of HCM derived based on the steady and balanced two-lane-two-way (TLTW) traffic flows. The objective of the study is to identify PCE values for TLTW highway at various traffic volume with an emphasis on congestion conditions. This study introduces an analytical model, combining a headway-based and a delay-based algorithms, for estimating PCEs of HV on a TLTW highway. This study contributes to the literature by providing relationships among PCE, the traffic volume level (TVL) of both lanes, and the TVL duration on a TLTW highway. Traffic volume was categorized into five levels: TVL A (<250 pc/h), TVL B (250–375 pc/h), TVL C (375–600 pc/h), TVL D (600–850 pc/h), and TVL E (>850 pc/h). The results indicate that on a TLTW highway, the TVLs of both lanes and their durations have significant impact on PCE values. In general, PCE values increase as TVL duration increases. Trucks have much higher impacts on operation under unbalanced conditions of TVL A with D, TVL B with C, and TVL D with B, when duration time is greater than one hour. When both lanes are saturated, trucks’ effect on capacity diminishes over time, and PCE values are approaching to 1.0.
Highlights
Introduction and Literature ReviewBecause of the recent oil boom in Western North Dakota, the number of large oil trucks on two-lane rural highways has increased dramatically to transport oil-related products. e sudden surge in the number of large trucks results in severe trafc issues related to highway design
Several interesting observations were discovered under these situations: (1) passenger car equivalent (PCE) increases as tra c volume level (TVL) duration increases which indicates that trucks will have increasingly more impact on tra c with congestion duration increasing when passing behavior is not an option for trucks, but is still possible for passenger cars
PCE impacts of traffic congestion levels and their durations of both lanes for a TLTW highway is under-researched in the literature. is research studied the impacts and developed a new recommended PCE values for heavy trucks on a TWTL highway with passing allowed. e following can be concluded for PCE on a two-way-two-lane highway: (1) Traffic congestion levels on both two lanes have significant impacts on PCE values and the impact is not independently existent. e same congestion level of analysis lane has significantly different values if the opposite lane congestion level varies
Summary
Introduction and Literature ReviewBecause of the recent oil boom in Western North Dakota, the number of large oil trucks on two-lane rural highways has increased dramatically to transport oil-related products. e sudden surge in the number of large trucks results in severe trafc issues related to highway design. Us, it is critical to measure such di erences to help the Department of Transportation (DOT) and other agencies with highway design and congestion challenges. E passenger car equivalent (PCE) factor is commonly used to assess di erences between large trucks and passenger cars in terms of highway capacity and congestion analysis [1]. PCE factor measures the magnitude of large vehicles’ e ect on following tra c compared to passenger cars [2]. Previous researchers developed numerous models to measure PCE factors, such as headway-based method [3], delay-based method [4, 5], average-travel speed-based method [6,7,8,9], truck-percentage-based method [10], density-based method [11], and time-spent-on-following-based method [12].
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