Safarov, Karam

English

A number of prior studies examine decentralised junction crossing methods, which aim to simulate future autonomous vehicles (AVs). However, very few consider scenarios where a mixed flow (human drivers and AVs) of vehicles crosses an unregulated junction. Thus this thesis aims to study scenarios where stylised models of human-drivers and models of AVs interact. Specifically, we study the anecdotal hypothesis that states the following: strict rule-following AVs might create bottlenecks at junctions by not being able to ‘read’ the intentions of human drivers [39, 185]. A possible solution, that we examine in this thesis, is to modify the AV control logic to mimic the ‘aggressive’ and ‘generous’ behaviours that human drivers use to overcome deadlocks. In order to study how the performance of an unregulated junction varies under different junction-crossing policies, we develop a simple MATLAB simulation of two intersecting one dimensional flows that can incorporate a variety of vehicle behaviours. Although our simulator lacks some of the detail present in commercial microsimulation software, it is designed with the appropriate level of parsimony to answer our key research questions, and to enable a rapid exploration of junction-crossing behaviours. We present the theoretical foundation of the simulation, which includes designing simple and modular control policies for mixed traffic simulation, which can be used to analyse junction performance. Throughout the thesis, our focus is on junction performance at a system level, and its dependence on a range of parameters that are chosen to represent ‘human-like’ or ‘AV-like’ decision-making behaviour. Broadly speaking—our simulation results show distinct crossing regimes at low, medium and high densities. The transitions between regimes can be predicted analytically, while their performance may be related to the classical fundamental diagram approach of one-dimensional traffic flow theory. Furthermore, mixed traffic analysis indicates that more ‘generous’ vehicles tend to improve junction performance. In contrast, ‘impatient’ ones tend to degrade the total throughput without intervention from the road infrastructure (i.e., centralised control elements). These findings have the potential to focus efforts on the development of improved decision-making rules for emerging AVs. Also, our work might help predict the impact of the gradual introduction of autonomous technology on our urban road system.<br/

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The impact of autonomous vehicles on traffic performance at an unregulated junction

https://research-information.bris.ac.uk/files/321140726/Final_Copy_2022_04_04_Safarov_K_PhD.pdf

The impact of autonomous vehicles on traffic performance at an unregulated junction

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