Impacts of Different Types of Automated Vehicles on Traffic Flow Characteristics and Emissions: A Microscopic Traffic Simulation of Different Freeway Segments

Abstract

Different types of automated vehicles (AVs) have emerged promptly in recent years, each of which might have different potential impacts on traffic flow and emissions. In this paper, the impacts of autonomous automated vehicles (AAVs) and cooperative automated vehicles (CAVs) on capacity, average traffic speed, average travel time per vehicle, and average delay per vehicle, as well as traffic emissions such as carbon dioxide (CO2), nitrogen oxides (NOx), and particulate matter (PM10) have been investigated through a microsimulation study in VISSIM. Moreover, the moderating effects of different AV market penetration, and different freeway segments on AV’s impacts have been studied. The simulation results show that CAVs have a higher impact on capacity improvement regardless of the type of freeway segment. Compared to other scenarios, CAVs at 100% market penetration in basic freeway segments have a greater capacity improvement than AAVs. Furthermore, merging, diverging, and weaving segments showed a moderating effect on capacity improvements, particularly on CAVs’ impact, with merging and weaving having the highest moderating effect on CAVs’ capacity improvement potential. Taking average delay per vehicle, average traffic speed, and average travel time per vehicle into account, simulation results were diverse across the investigated scenarios. The emission estimation results show that 100% AAV scenarios had the best performance in emission reductions in basic freeway and merging sections, while other scenarios increased emissions in diverging and weaving sections.

How PTV Vissim Has Been Calibrated for the Simulation of Automated Vehicles in Literature?

“…In the literature, different driving behaviours of AVs have been assumed; for example, they can be grouped as cautious and aggressive [7,50,51] based on the levels of automation, where level 5 represents the most aggressive AVs. AVs can be further clustered as cooperative/connected AVs (CAVs) and autonomous (without communication capability) AVs (AAVs) [12,11]. What is more, the types of roadway have a significant impact on the driving characteristics of AVs, as the study [22], for example, showed that vehicles are more conservative on basic freeways than on merging and diverging freeway segments.…”

“…Furthermore, in the literature, two primary streams of studies use Vissim to replicate the driving behaviours of AVs using either internal or external modelling techniques. e first stream (e.g., see [7,12,25,32]) uses the internal modelling, and modifies the default Wiedemann driving logic (car-following) and lane-changing parameters to simulate the desired driving behaviours. e second stream, which uses the external Vissim interfaces and the external modelling methodology, sends user-defined algorithms to a dynamic link library to imitate the driving logic of AVs (e.g., see [33,34]).…”

“…However, the term "automated vehicle" implies a vehicle system that may be controlled at several levels and does not necessarily need to be fully automated with no human driver interaction under all circumstances [9]. Furthermore, the study by Sala and Soriguera [10] considered "connected autonomous" to describe to vehicles that are fully automated and can communicate with their environment, while studies [11,12] used "autonomous automated vehicles" and "cooperative automated vehicles." us, looking at the large body of works of literature (e.g., [10,[12][13]), the two types of fully automated vehicles are autonomous (without communication capabilities), automated vehicles (AAVs), and cooperative/connected automated vehicles (CAVs).…”

“…Furthermore, the study by Sala and Soriguera [10] considered "connected autonomous" to describe to vehicles that are fully automated and can communicate with their environment, while studies [11,12] used "autonomous automated vehicles" and "cooperative automated vehicles." us, looking at the large body of works of literature (e.g., [10,[12][13]), the two types of fully automated vehicles are autonomous (without communication capabilities), automated vehicles (AAVs), and cooperative/connected automated vehicles (CAVs). AAVs merely use their own sensors to gather information, but CAVs combine all AAV features with vehicle-to-vehicle and vehicle-to-infrastructure communication to augment the data from their sensors.…”

Macroscopic Experiments on Coexistence of Autonomous Vehicle Behavior on Various Heterogeneous Traffic Conditions

“…It is expected that the proportion of AVs would gradually increase in the near future, which initially coexist with conventional vehicles (CVs) under mixed traffic condition [1][2][3][4]. Although there are still many unanswered questions regarding the precise effects of AVs on energy and the environment, it is generally acknowledged that at increasing AV penetration, a substantial net decrease in greenhouse gas emissions can be achieved [5][6][7][8]. e heterogeneous blend of AVs and CVs will undoubtedly have a substantial impact on traffic performance.…”