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A Methodology for Estimating Capacity and Passenger Car Equivalents for Connected and Automated Vehicles Traveling on Freeways

Antonio Hurtado-Beltran, University of Nebraska - Lincoln


Recently, there has been a significant amount of research related to heavy trucks operating as connected and autonomous vehicles (CAVs). In order to understand the potential impact on the freeway system of CAV technologies, analyses should be conducted using the standard US methodological framework. In the current version of the Highway Capacity Manual (HCM-6), equal-capacity passenger car equivalencies (EC-PCEs) are used to account for the effect of heavy trucks on capacity and quality of service analyses. It is argued in this dissertation the HCM-6 EC-PCE methodology for basic freeway and multilane highway segments can be used to explore a wide variety of traffic situations beyond the scope of the existing results including those related to CAV technologies. However, there are various shortcomings to address before applying the methodology for these purposes. This dissertation develops new strategies to improve the current state-of-the-art methodology for estimating freeway capacity and PCEs. The end result is a new modeling methodology that can be used to analyze new traffic scenarios including connected and automated vehicles (CAVs). Specifically, this dissertation develops consistent metrics for the HCM-6, introduces simpler regression model structures for fitting simulated and estimated data, and proposes a replicable microsimulation framework. The proposed improvements are examined for both CAV and non-CAV conditions on unidirectional two-lane and three-lane freeway segments. In general, it was found EC-PCE values for CAV trucks are, on average, between 24% and 34% lower compared to the values for non-CAV trucks, indicating that CAV platoons can have a positive effect on freeway capacity. Additionally, it was demonstrated the proposed approaches can be successfully applied to the estimation of EC-PCEs. The new techniques proposed for capacity modeling and EC-PCE estimation can be used by engineers and traffic agencies for analyzing any traffic condition outside the HCM-6. It is vital all future EC-PCE analyses are performed using the same standard methodological framework to produce comparable results that can be applied consistently in the HCM-6.

Subject Area

Civil engineering|Transportation

Recommended Citation

Hurtado-Beltran, Antonio, "A Methodology for Estimating Capacity and Passenger Car Equivalents for Connected and Automated Vehicles Traveling on Freeways" (2021). ETD collection for University of Nebraska-Lincoln. AAI28418323.