B. van Arem
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58 records found
1
To address this challenge, the thesis adopts the philosophical framework of Meaningful Human Control (MHC), which requires that automated systems both track relevant human reasons and allow responsibility for outcomes to be meaningfully traced to human agents. While MHC has been widely discussed at a conceptual level, its technical operationalisation in automated driving remains underdeveloped. This dissertation advances MHC by translating its normative principles into an integrated framework that connects ethical reasoning, engineering implementation, and empirical evaluation.
The dissertation first investigates which human reasons are relevant for automated-vehicle manoeuvre planning in ethically ambiguous, everyday traffic situations. Empirical findings from interviews with AV experts show that such reasons are inherently multi-layered, context-dependent, and often simultaneous, spanning normative, strategic, tactical, and operational considerations. Rather than functioning as fixed values or isolated cost terms, human reasons are shown to form context-sensitive relationships between underlying motivations and expected vehicle behaviour. These insights provide an empirically grounded basis for structuring and prioritising human reasons in automated-vehicle decision-making.
Building on this foundation, the dissertation develops a technical approach for embedding human reasons within automated-vehicle control architectures. Human reasons are translated into formal, machine-readable representations by drawing on insights from human-factors research and are integrated through a supervisory evaluation layer that operates alongside existing motion planning and control frameworks. This approach enables transparent trajectory evaluation and adaptive behavioural adjustment without requiring the design of new controllers, thereby demonstrating a practical pathway for operationalising MHC in real-time decision-making systems.
Finally, the dissertation examines whether meaningful human control can be empirically assessed in practice. Qualitative studies with users of partially automated driving systems reveal how the tracking and tracing conditions of MHC manifest dynamically in drivers’ experiences of safety, trust, responsibility, and intervention readiness. Complementary simulator experiments show that objective behavioural telemetry can capture aspects of tracking at the level of concrete interaction events, while tracing cannot be inferred from behaviour alone. Together, these findings demonstrate that meaningful human control is not merely a normative or post-hoc concept, but an empirically observable property of ongoing human–automation interaction when evaluated through a multi-layer framework combining subjective perception and objective data.
Overall, this dissertation advances the technical operationalisation of meaningful human control by systematically linking human reasons, automated-vehicle decision-making, and empirical evaluation. The proposed framework provides researchers, designers, and policymakers with concrete tools to assess and support reason-aligned automated-vehicle behaviour, contributing to the development of automated driving systems whose behaviour is more transparent, context-sensitive, and reasonable in everyday traffic situations.
...
To address this challenge, the thesis adopts the philosophical framework of Meaningful Human Control (MHC), which requires that automated systems both track relevant human reasons and allow responsibility for outcomes to be meaningfully traced to human agents. While MHC has been widely discussed at a conceptual level, its technical operationalisation in automated driving remains underdeveloped. This dissertation advances MHC by translating its normative principles into an integrated framework that connects ethical reasoning, engineering implementation, and empirical evaluation.
The dissertation first investigates which human reasons are relevant for automated-vehicle manoeuvre planning in ethically ambiguous, everyday traffic situations. Empirical findings from interviews with AV experts show that such reasons are inherently multi-layered, context-dependent, and often simultaneous, spanning normative, strategic, tactical, and operational considerations. Rather than functioning as fixed values or isolated cost terms, human reasons are shown to form context-sensitive relationships between underlying motivations and expected vehicle behaviour. These insights provide an empirically grounded basis for structuring and prioritising human reasons in automated-vehicle decision-making.
Building on this foundation, the dissertation develops a technical approach for embedding human reasons within automated-vehicle control architectures. Human reasons are translated into formal, machine-readable representations by drawing on insights from human-factors research and are integrated through a supervisory evaluation layer that operates alongside existing motion planning and control frameworks. This approach enables transparent trajectory evaluation and adaptive behavioural adjustment without requiring the design of new controllers, thereby demonstrating a practical pathway for operationalising MHC in real-time decision-making systems.
Finally, the dissertation examines whether meaningful human control can be empirically assessed in practice. Qualitative studies with users of partially automated driving systems reveal how the tracking and tracing conditions of MHC manifest dynamically in drivers’ experiences of safety, trust, responsibility, and intervention readiness. Complementary simulator experiments show that objective behavioural telemetry can capture aspects of tracking at the level of concrete interaction events, while tracing cannot be inferred from behaviour alone. Together, these findings demonstrate that meaningful human control is not merely a normative or post-hoc concept, but an empirically observable property of ongoing human–automation interaction when evaluated through a multi-layer framework combining subjective perception and objective data.
Overall, this dissertation advances the technical operationalisation of meaningful human control by systematically linking human reasons, automated-vehicle decision-making, and empirical evaluation. The proposed framework provides researchers, designers, and policymakers with concrete tools to assess and support reason-aligned automated-vehicle behaviour, contributing to the development of automated driving systems whose behaviour is more transparent, context-sensitive, and reasonable in everyday traffic situations.
On the Bright Side of Vehicle Automation
The effects of service quality improvements and ride experience on users’ preferences for automated public transport
Determining the optimal stop and line spacing of an urban bus network for different area types
A weighted total travel time model for optimising the bus stop and line spacing for different urban area types based on sociodemographic characteristics
The focus of this thesis is the stop and line spacing of the bus, the distance between sequential bus stop and parallel bus lines respectively. Changing the stop and line spacing have an effect on the running time of bus users, with a trade-off between the walking and in-vehicle time. A self-designed total travel time model optimises the weighted total travel time with weights on the walking time and frequency. The frequency here is based on a combination of stop and line spacing. The stop and line spacing affect the running time and thus how much a vehicle serves a route per hour. This in turn determines the frequency. The result of the total travel time model is an optimal stop spacing of around 540 meter and a line spacing of 700 meter. Analytical models by other researchers found an optimum stop spacing in between 600 and 650 meter and a line spacing of 750 meter. In practice guidelines are used where the stop spacing is around 400 meter and the line spacing is around 550 meter. The result of the self-designed model is different because the walking weight is exponential and the frequency weight is tied to the running time of the bus. The conclusion is that the optimal stop spacing is higher than is mostly applied in bus networks. A higher stop spacing means a higher average speed and a lower travel time in the bus. The downside of a higher stop spacing is that the walking distance increases which effects the ridership. This is the reason the self-designed total travel time model has a larger focus on the walking distance, and has resulted in a lower optimal stop and line spacing than in analytical models of other researchers.
The effect the walking distance has on the use of the bus is different in different area types in an urban agglomeration. A regression analysis on the relation between the stop spacing and sociodemographic characteristics has been performed for the analysis of this effect. The data used for the regression analysis is gathered for the city of Rotterdam and the surrounding towns. For an area with a high population density, income, and car ownership in combination with a large distance, around 10 km, from the city center a stop spacing of 600 to 700 meter is recommended. The lower the distance to the city center, the lower the stop spacing, and thus for a similar area type around 5 km from the city center a stop spacing of 500 to 550 meter is recommended. For an area with an average population density, income and car ownership in combination with a high distance (10 km) to the city center a stop spacing of 475 to 525 meter and in combination with a lower distance (5 km) a stop spacing of 450 to 475 meter is recommended. The reason why these values are lower than for the first area type is because there are more activity facilities. This means that there are more potential destinations in this area type and for users a stop close to a destination is important for the choice to use public transport. The larger the area of these facilities, and the higher the number of facilities, the lower the stop spacing. In the city center the recommended stop spacing is therefore 425 to 450 meter. The exception to this is the area close to the central station of Rotterdam, here the stop spacing is higher (550 to 600 meter) because close to a station people are not going to use the bus, but the train which has a higher operation speed and thus is a higher quality mode. For an area with a low population density, income and car ownership a stop spacing of 550 to 650 meter is recommended. In this area type there are a lot of captive riders, who are dependent on public transport and are willing to walk further than other types of public transport users. For this group it is important that bus stops are close to activity centers. If the stop spacing in this area becomes too high the number of trips made by captives decreases, even if the number of users stays the same. Having bus stops close to destinations compensate for the higher stop spacing. These destinations could also be a train, metro and/or tram stop. This complies with the higher willingness to walk, and makes the bus network more efficient.
For the line spacing it is more complicated to recommend values for certain area types. However recommendations are given to the network type and design, which is closely related to the line spacing. Because different area types have different characteristics a hybrid network is the most effective solution. In the city center a grid network is used to distribute users equally. Radial lines are used to connect areas outside the city center with the city center and ring lines are used to create connections between these areas if the demand for this is there. The further away from the city center the lower the bus stop density.
...
The focus of this thesis is the stop and line spacing of the bus, the distance between sequential bus stop and parallel bus lines respectively. Changing the stop and line spacing have an effect on the running time of bus users, with a trade-off between the walking and in-vehicle time. A self-designed total travel time model optimises the weighted total travel time with weights on the walking time and frequency. The frequency here is based on a combination of stop and line spacing. The stop and line spacing affect the running time and thus how much a vehicle serves a route per hour. This in turn determines the frequency. The result of the total travel time model is an optimal stop spacing of around 540 meter and a line spacing of 700 meter. Analytical models by other researchers found an optimum stop spacing in between 600 and 650 meter and a line spacing of 750 meter. In practice guidelines are used where the stop spacing is around 400 meter and the line spacing is around 550 meter. The result of the self-designed model is different because the walking weight is exponential and the frequency weight is tied to the running time of the bus. The conclusion is that the optimal stop spacing is higher than is mostly applied in bus networks. A higher stop spacing means a higher average speed and a lower travel time in the bus. The downside of a higher stop spacing is that the walking distance increases which effects the ridership. This is the reason the self-designed total travel time model has a larger focus on the walking distance, and has resulted in a lower optimal stop and line spacing than in analytical models of other researchers.
The effect the walking distance has on the use of the bus is different in different area types in an urban agglomeration. A regression analysis on the relation between the stop spacing and sociodemographic characteristics has been performed for the analysis of this effect. The data used for the regression analysis is gathered for the city of Rotterdam and the surrounding towns. For an area with a high population density, income, and car ownership in combination with a large distance, around 10 km, from the city center a stop spacing of 600 to 700 meter is recommended. The lower the distance to the city center, the lower the stop spacing, and thus for a similar area type around 5 km from the city center a stop spacing of 500 to 550 meter is recommended. For an area with an average population density, income and car ownership in combination with a high distance (10 km) to the city center a stop spacing of 475 to 525 meter and in combination with a lower distance (5 km) a stop spacing of 450 to 475 meter is recommended. The reason why these values are lower than for the first area type is because there are more activity facilities. This means that there are more potential destinations in this area type and for users a stop close to a destination is important for the choice to use public transport. The larger the area of these facilities, and the higher the number of facilities, the lower the stop spacing. In the city center the recommended stop spacing is therefore 425 to 450 meter. The exception to this is the area close to the central station of Rotterdam, here the stop spacing is higher (550 to 600 meter) because close to a station people are not going to use the bus, but the train which has a higher operation speed and thus is a higher quality mode. For an area with a low population density, income and car ownership a stop spacing of 550 to 650 meter is recommended. In this area type there are a lot of captive riders, who are dependent on public transport and are willing to walk further than other types of public transport users. For this group it is important that bus stops are close to activity centers. If the stop spacing in this area becomes too high the number of trips made by captives decreases, even if the number of users stays the same. Having bus stops close to destinations compensate for the higher stop spacing. These destinations could also be a train, metro and/or tram stop. This complies with the higher willingness to walk, and makes the bus network more efficient.
For the line spacing it is more complicated to recommend values for certain area types. However recommendations are given to the network type and design, which is closely related to the line spacing. Because different area types have different characteristics a hybrid network is the most effective solution. In the city center a grid network is used to distribute users equally. Radial lines are used to connect areas outside the city center with the city center and ring lines are used to create connections between these areas if the demand for this is there. The further away from the city center the lower the bus stop density.
Safe, Efficient, and Socially Compliant Automated Driving in Mixed Traffic
Sensing, Anomaly Detection, Planning and Control
The steady development of automated vehicles (AVs) promises significant benefits in terms of traffic safety and efficiency. However, the transition to fully AVs and their deployment on the road will be gradual, leading to a phase of mixed-traffic conditions where AVs at various levels coexist with human-driven vehicles (HDVs). This transition poses unprecedented hurdles, requiring a deeper understanding of the emerging challenges for AVs in sensing and perceiving road environments, as well as in the novel interactions between AVs and HDVs. Furthermore, the social compliance of AVs and the optimization of their deployment strategies need to be considered as well.
Contents of this Thesis
This thesis addresses the multifaceted challenges associated with AVs’ development and deployment in mixed-traffic environments. The main objective of this thesis is to enhance the capabilities of AVs enabling them with a wider Operational Design Domain (ODD) and thus facilitate the implementation of safe, efficient, and socially compliant automated driving in mixed traffic. Referring to the modular design of AV systems, three key perspectives, i.e., sensing and perception, anomaly detection, as well as planning and control, are tackled in this thesis. To be specific:
Chapters 2-4 focus on enhancing sensing and perception capabilities through the development of hybrid spatial-temporal deep learning models and self-supervised pretraining methods. Lane detection is chosen as the focus of these chapters since it is vital for current vehicle localization and positioning, and it is also the foundation of various automated driving features. The main findings of these chapters are summarized as follows.
Chapter 2 presents a pioneering hybrid spatial-temporal sequence-to-one deep learning architecture tailored for vision-based lane detection tasks. By integrating the spatial convolutional neural network (SCNN) with spatial-temporal Recurrent Neural Network (RNN) modules, this architecture effectively captures correlations and dependencies among continuous image frames. Through extensive experimentation on various driving scenes, including challenging scenarios, the proposed model variants exhibit superior performance over existing state-of-the-art models. Notably, even the lighter model variants demonstrate remarkable accuracy, outperforming their counterparts while maintaining lower computational complexity.
Building upon the foundation laid in Chapter 2, Chapter 3 focuses on refining vision-based sensing and perception through the development of customized spatial-temporal attention mechanisms. These mechanisms, including temporal attention, spatial-temporal attention, and spatial-temporal attention with fully connected layers, are meticulously designed to optimize the utilization of spatial-temporal correlations across different regions of interest within the consecutive image frames. Leveraging linear Long Short Term Memory (LSTM) neural networks in conjunction with the proposed attention blocks, this chapter demonstrates the feasibility of lightweight and computationally efficient solutions for sequential deep neural networks (DNNs). Through rigorous experimentation, ablation studies, and comparative analysis across diverse datasets, the effectiveness of the proposed attention mechanisms in enhancing lane detection performance is convincingly established.
In Chapter 4, the exploration of enhancing vision-based sensing and perception capabilities continues with the introduction of a self-supervised pretraining method employing masked sequential autoencoders (MSAE). This innovative approach leverages both labelled and unlabelled data to improve detection accuracy and expedite the training process of DNN models dedicated to lane detection tasks. Additionally, a customized Focal Loss based PolyLoss is introduced to further enhance the detection accuracy. Through comprehensive experimentation and comparative analysis, the efficacy of the proposed pretraining method and loss function is demonstrated, showcasing substantial improvements in lane detection performance across diverse driving scenarios. Specifically, the utilization of MSAE-based pretraining and the adoption of the customized PolyLoss result in superior performance metrics, underscoring the pivotal role of self-supervised learning techniques and tailored loss functions in fortifying the robustness and efficiency of vision-based sensing and perception systems in AVs.
These chapters address the challenges of vision-based lane detection, crucial for AV navigation and safety.
Chapters 5-6 delve into anomaly detection, investigating techniques for identifying abnormal lane rendering in digital map applications and detecting anomalies in driving behaviour.
Chapter 5 introduces an innovative approach to anomaly detection in lane rendering images of digital map applications, utilizing Transformer-based models with self-supervised pretraining and customized fine-tuning. By transforming anomaly detection into a classification problem, the chapter proposes a four-phase pipeline that includes data pre-processing, self-supervised pre-training with masked image modelling (MiM), customized fine-tuning using cross-entropy-based loss, and post-processing. Experimental results demonstrate the pipeline’s effectiveness, with significant improvements in detection accuracy and reduced training time achieved through self-supervised pre-training. Ablation studies regarding tackling the problem with different numbers of classes further validate the pipeline’s performance enhancements, particularly in addressing data imbalance. This approach not only enhances anomaly detection accuracy but also contributes to reducing labour costs associated with manual labelling and anomaly detection efforts, offering significant societal benefits.
Additionally, Chapter 6 explores the critical task of detecting abnormal driving behaviour, addressing the need for more feasible and efficient approaches by leveraging semi-supervised ML methods. Utilizing large-scale real-world driving data, the study develops a semi-supervised ML model based on Hierarchical Extreme Learning Machines (HELM). This approach utilizes partly labelled data and introduces Surrogate Safety Measures (SSMs) (specifically the event-baed safety indicators of Two-Dimensional Time-To-Collision (2D-TTC)) as the pivotal input features to enhance performance. Results demonstrate the effectiveness of the proposed semi-supervised ML model, showcasing superior performance compared to baseline methods. The integration of SSMs significantly improves detection accuracy, highlighting their significant role in enhancing model performance. By leveraging unlabelled data for training and only a small sample of labelled data for fine-tuning, the proposed semi-supervised approach achieves competitive performance while reducing dependency on fully labelled datasets, making it suitable for real-world applications.
To sum up, the exploration of semi-supervised and self-supervised ML methods presents promising avenues in anomaly detection. The pioneering research presented in this thesis represents a significant stride towards leveraging data-driven ML-based anomaly detection methodologies to enhance the safety of driving.
Chapters 7-9 shift the focus to planning and control strategies for AVs, presenting a comprehensive examination of decision-making frameworks and control algorithms. These chapters introduce a conceptual framework aimed at fostering socially compliant driving behaviour and propose a range of model-based and learning-based approaches.
Chapter 7 lays the groundwork by introducing a conceptual framework that emphasizes socially compliant automated driving. This framework encompasses various social components such as cultural nuances, norms, and driving styles. A key innovation is the introduction of bidirectional behavioural adaptation, highlighting the dynamic interactions between AVs and human drivers. Furthermore, the framework advocates for the incorporation of a spatial-temporal memory module to enable continuous refinement of driving strategies, thereby promoting adaptability and safety in diverse traffic scenarios. Validation through an online expert survey lends credence to the framework’s efficacy. This conceptual framework lays a solid foundation for learning-based and model-based approaches for implementing planning and control algorithms for automated driving.
In the learning-based approach explored in Chapter 8, Deep Reinforcement Learning (DRL) takes centre stage, with a focus on integrating safety, efficiency, comfort level, and energy consumption considerations into the learning framework. Multiple DRL algorithms are evaluated across diverse driving manoeuvres, particularly roundabout driving, highlighting the importance of real-world requirements in reward function design and simulation-based training. Among the compared DRL algorithms, Trust Region Policy Optimization (TRPO) emerges as leading in safety and efficiency, while Proximal Policy Optimization (PPO) excels in comfort during roundabout driving. Moreover, the extension of the training environment to encompass various driving scenarios showcases the adaptability of DRL models to train a uniform driving model for real traffic environments, signalling promising avenues for future research.
Regarding the model-based approach, Chapter 9 introduces the DRF-SVO-MPCC algorithm, aimed at enhancing AVs’ understandability and predictability to human drivers, particularly during interactions with HDVs when driving through the roundabouts, as this challenging manoeuvre involves large curvature and tackles both longitudinal and lateral control. This algorithm integrates the perceived Driving Risk Field (DRF), Social Value Orientation (SVO), and Model Predictive Contouring Control (MPCC), enabling AVs to navigate social scenarios with sensitivity to the welfare of surrounding HDVs. Simulation experiments, conducted on various roundabout scenarios, underscore the algorithm’s superiority in trajectory tracking and adaptability to different driving styles, ensuring safety and social compliance. The findings illuminate the potential of the DRF-SVO-MPCC algorithm in fostering harmonious interactions between AVs and HDVs, setting a precedent for socially aware automated driving systems.
Overall, this thesis represents a solid endeavour to advance the planning and control capabilities of AVs in mixed-traffic environments. Through the development of novel conceptual frameworks and innovative model-based and learning-based algorithmic solutions, it lays the groundwork for the realization of safe, efficient, socially compliant, and adaptable automated driving, contributing to safer and more harmonious transportation systems.
Conclusion and perspectives
In summary, this thesis contributes to advancing the knowledge of how to improve automated driving systems in the realms of sensing and perception, anomaly detection, as well as planning and control. By integrating theoretical frameworks, methodological innovations, and data-driven empirical evaluations, notable progress has been achieved in fostering the development of safe, efficient, and socially compliant automated driving within mixed-traffic environments.
Despite the considerable progress made, several directions for future research have been identified. These include the imperative for more expansive high-quality datasets, exploration of domain adaptation techniques for both sensing and anomaly detection tasks, as well as the seamless integration of model-based and learning-based methodologies for planning and control. Additionally, transitioning towards a unified driving model and effectively addressing the complexities of multi-agent interactions in intricate urban settings remain pivotal areas for further exploration. Furthermore, interdisciplinary collaboration will be instrumental in harnessing the full potential of automated vehicles to revolutionize transportation systems.
...
The steady development of automated vehicles (AVs) promises significant benefits in terms of traffic safety and efficiency. However, the transition to fully AVs and their deployment on the road will be gradual, leading to a phase of mixed-traffic conditions where AVs at various levels coexist with human-driven vehicles (HDVs). This transition poses unprecedented hurdles, requiring a deeper understanding of the emerging challenges for AVs in sensing and perceiving road environments, as well as in the novel interactions between AVs and HDVs. Furthermore, the social compliance of AVs and the optimization of their deployment strategies need to be considered as well.
Contents of this Thesis
This thesis addresses the multifaceted challenges associated with AVs’ development and deployment in mixed-traffic environments. The main objective of this thesis is to enhance the capabilities of AVs enabling them with a wider Operational Design Domain (ODD) and thus facilitate the implementation of safe, efficient, and socially compliant automated driving in mixed traffic. Referring to the modular design of AV systems, three key perspectives, i.e., sensing and perception, anomaly detection, as well as planning and control, are tackled in this thesis. To be specific:
Chapters 2-4 focus on enhancing sensing and perception capabilities through the development of hybrid spatial-temporal deep learning models and self-supervised pretraining methods. Lane detection is chosen as the focus of these chapters since it is vital for current vehicle localization and positioning, and it is also the foundation of various automated driving features. The main findings of these chapters are summarized as follows.
Chapter 2 presents a pioneering hybrid spatial-temporal sequence-to-one deep learning architecture tailored for vision-based lane detection tasks. By integrating the spatial convolutional neural network (SCNN) with spatial-temporal Recurrent Neural Network (RNN) modules, this architecture effectively captures correlations and dependencies among continuous image frames. Through extensive experimentation on various driving scenes, including challenging scenarios, the proposed model variants exhibit superior performance over existing state-of-the-art models. Notably, even the lighter model variants demonstrate remarkable accuracy, outperforming their counterparts while maintaining lower computational complexity.
Building upon the foundation laid in Chapter 2, Chapter 3 focuses on refining vision-based sensing and perception through the development of customized spatial-temporal attention mechanisms. These mechanisms, including temporal attention, spatial-temporal attention, and spatial-temporal attention with fully connected layers, are meticulously designed to optimize the utilization of spatial-temporal correlations across different regions of interest within the consecutive image frames. Leveraging linear Long Short Term Memory (LSTM) neural networks in conjunction with the proposed attention blocks, this chapter demonstrates the feasibility of lightweight and computationally efficient solutions for sequential deep neural networks (DNNs). Through rigorous experimentation, ablation studies, and comparative analysis across diverse datasets, the effectiveness of the proposed attention mechanisms in enhancing lane detection performance is convincingly established.
In Chapter 4, the exploration of enhancing vision-based sensing and perception capabilities continues with the introduction of a self-supervised pretraining method employing masked sequential autoencoders (MSAE). This innovative approach leverages both labelled and unlabelled data to improve detection accuracy and expedite the training process of DNN models dedicated to lane detection tasks. Additionally, a customized Focal Loss based PolyLoss is introduced to further enhance the detection accuracy. Through comprehensive experimentation and comparative analysis, the efficacy of the proposed pretraining method and loss function is demonstrated, showcasing substantial improvements in lane detection performance across diverse driving scenarios. Specifically, the utilization of MSAE-based pretraining and the adoption of the customized PolyLoss result in superior performance metrics, underscoring the pivotal role of self-supervised learning techniques and tailored loss functions in fortifying the robustness and efficiency of vision-based sensing and perception systems in AVs.
These chapters address the challenges of vision-based lane detection, crucial for AV navigation and safety.
Chapters 5-6 delve into anomaly detection, investigating techniques for identifying abnormal lane rendering in digital map applications and detecting anomalies in driving behaviour.
Chapter 5 introduces an innovative approach to anomaly detection in lane rendering images of digital map applications, utilizing Transformer-based models with self-supervised pretraining and customized fine-tuning. By transforming anomaly detection into a classification problem, the chapter proposes a four-phase pipeline that includes data pre-processing, self-supervised pre-training with masked image modelling (MiM), customized fine-tuning using cross-entropy-based loss, and post-processing. Experimental results demonstrate the pipeline’s effectiveness, with significant improvements in detection accuracy and reduced training time achieved through self-supervised pre-training. Ablation studies regarding tackling the problem with different numbers of classes further validate the pipeline’s performance enhancements, particularly in addressing data imbalance. This approach not only enhances anomaly detection accuracy but also contributes to reducing labour costs associated with manual labelling and anomaly detection efforts, offering significant societal benefits.
Additionally, Chapter 6 explores the critical task of detecting abnormal driving behaviour, addressing the need for more feasible and efficient approaches by leveraging semi-supervised ML methods. Utilizing large-scale real-world driving data, the study develops a semi-supervised ML model based on Hierarchical Extreme Learning Machines (HELM). This approach utilizes partly labelled data and introduces Surrogate Safety Measures (SSMs) (specifically the event-baed safety indicators of Two-Dimensional Time-To-Collision (2D-TTC)) as the pivotal input features to enhance performance. Results demonstrate the effectiveness of the proposed semi-supervised ML model, showcasing superior performance compared to baseline methods. The integration of SSMs significantly improves detection accuracy, highlighting their significant role in enhancing model performance. By leveraging unlabelled data for training and only a small sample of labelled data for fine-tuning, the proposed semi-supervised approach achieves competitive performance while reducing dependency on fully labelled datasets, making it suitable for real-world applications.
To sum up, the exploration of semi-supervised and self-supervised ML methods presents promising avenues in anomaly detection. The pioneering research presented in this thesis represents a significant stride towards leveraging data-driven ML-based anomaly detection methodologies to enhance the safety of driving.
Chapters 7-9 shift the focus to planning and control strategies for AVs, presenting a comprehensive examination of decision-making frameworks and control algorithms. These chapters introduce a conceptual framework aimed at fostering socially compliant driving behaviour and propose a range of model-based and learning-based approaches.
Chapter 7 lays the groundwork by introducing a conceptual framework that emphasizes socially compliant automated driving. This framework encompasses various social components such as cultural nuances, norms, and driving styles. A key innovation is the introduction of bidirectional behavioural adaptation, highlighting the dynamic interactions between AVs and human drivers. Furthermore, the framework advocates for the incorporation of a spatial-temporal memory module to enable continuous refinement of driving strategies, thereby promoting adaptability and safety in diverse traffic scenarios. Validation through an online expert survey lends credence to the framework’s efficacy. This conceptual framework lays a solid foundation for learning-based and model-based approaches for implementing planning and control algorithms for automated driving.
In the learning-based approach explored in Chapter 8, Deep Reinforcement Learning (DRL) takes centre stage, with a focus on integrating safety, efficiency, comfort level, and energy consumption considerations into the learning framework. Multiple DRL algorithms are evaluated across diverse driving manoeuvres, particularly roundabout driving, highlighting the importance of real-world requirements in reward function design and simulation-based training. Among the compared DRL algorithms, Trust Region Policy Optimization (TRPO) emerges as leading in safety and efficiency, while Proximal Policy Optimization (PPO) excels in comfort during roundabout driving. Moreover, the extension of the training environment to encompass various driving scenarios showcases the adaptability of DRL models to train a uniform driving model for real traffic environments, signalling promising avenues for future research.
Regarding the model-based approach, Chapter 9 introduces the DRF-SVO-MPCC algorithm, aimed at enhancing AVs’ understandability and predictability to human drivers, particularly during interactions with HDVs when driving through the roundabouts, as this challenging manoeuvre involves large curvature and tackles both longitudinal and lateral control. This algorithm integrates the perceived Driving Risk Field (DRF), Social Value Orientation (SVO), and Model Predictive Contouring Control (MPCC), enabling AVs to navigate social scenarios with sensitivity to the welfare of surrounding HDVs. Simulation experiments, conducted on various roundabout scenarios, underscore the algorithm’s superiority in trajectory tracking and adaptability to different driving styles, ensuring safety and social compliance. The findings illuminate the potential of the DRF-SVO-MPCC algorithm in fostering harmonious interactions between AVs and HDVs, setting a precedent for socially aware automated driving systems.
Overall, this thesis represents a solid endeavour to advance the planning and control capabilities of AVs in mixed-traffic environments. Through the development of novel conceptual frameworks and innovative model-based and learning-based algorithmic solutions, it lays the groundwork for the realization of safe, efficient, socially compliant, and adaptable automated driving, contributing to safer and more harmonious transportation systems.
Conclusion and perspectives
In summary, this thesis contributes to advancing the knowledge of how to improve automated driving systems in the realms of sensing and perception, anomaly detection, as well as planning and control. By integrating theoretical frameworks, methodological innovations, and data-driven empirical evaluations, notable progress has been achieved in fostering the development of safe, efficient, and socially compliant automated driving within mixed-traffic environments.
Despite the considerable progress made, several directions for future research have been identified. These include the imperative for more expansive high-quality datasets, exploration of domain adaptation techniques for both sensing and anomaly detection tasks, as well as the seamless integration of model-based and learning-based methodologies for planning and control. Additionally, transitioning towards a unified driving model and effectively addressing the complexities of multi-agent interactions in intricate urban settings remain pivotal areas for further exploration. Furthermore, interdisciplinary collaboration will be instrumental in harnessing the full potential of automated vehicles to revolutionize transportation systems.
Setting the Price for Carsharing
A Cost-Benefit Analysis of Equitable Carsharing in the Car-free Neighbourhood of Merwede
Planning the route to higher bus quality
Creating a roadmap for effective implementation of high-quality bus systems in the Netherlands
In this thesis, through a literature review and interviews with Dutch stakeholders, a definition of the high-quality bus system is found, including its main characteristics. The most important part of this thesis is to map the existing problems. In order to solve these problems, a roadmap is designed to help with the implementation by breaking the process down into smaller, more manageable steps.
A high-quality bus system should above all be fast, frequent, and reliable, but comfort is also important for such a system. The most commonly used terms are Bus Rapid Transit (BRT) and Bus with a High Level of Service (BHLS). The literature and the interviews confirm that there are still many problems that should be addressed in the roadmap, from cooperation problems to short-term thinking by politicians, from blind commitment to rail to underestimating the social value of public transport.
The proposed roadmap consists of eight blocks. It begins with the creation of a city-wide vision for mobility and the formulation of a programme of requirements for the entire public transport system (i). These are translated into objectives and a programme of requirements for the line to be designed (ii). In addition, cooperation with all parties should be well regulated (iii). The next important step is to analyse the target group of (potential) passengers, the stops and the bottlenecks and intersections (iv). Only after that is the system choice made (v). If a high-quality bus system is chosen, it needs to be designed (vi). Among other things, the route, the operation, the first/last mile transport and the branding have to be designed. When the design is ready, the line can be built, and operation can begin (vii). This can be done in stages, addressing the main bottlenecks first and the rest later. This is followed by the often overlooked evaluation, which is important for learning lessons for future projects.
Stakeholder feedback and a case study show the value of the roadmap for implementation in the Netherlands. By choosing the modality later in the process, compromises in quality are avoided. In addition, the in-depth analyses improve the quality of the line and enable faster implementation by identifying the main bottlenecks. The main value of the roadmap lies in its integral approach, rather than an approach from one perspective. This means that the problems of all stakeholders can be addressed to design a high-quality public transport system that works for all. ...
In this thesis, through a literature review and interviews with Dutch stakeholders, a definition of the high-quality bus system is found, including its main characteristics. The most important part of this thesis is to map the existing problems. In order to solve these problems, a roadmap is designed to help with the implementation by breaking the process down into smaller, more manageable steps.
A high-quality bus system should above all be fast, frequent, and reliable, but comfort is also important for such a system. The most commonly used terms are Bus Rapid Transit (BRT) and Bus with a High Level of Service (BHLS). The literature and the interviews confirm that there are still many problems that should be addressed in the roadmap, from cooperation problems to short-term thinking by politicians, from blind commitment to rail to underestimating the social value of public transport.
The proposed roadmap consists of eight blocks. It begins with the creation of a city-wide vision for mobility and the formulation of a programme of requirements for the entire public transport system (i). These are translated into objectives and a programme of requirements for the line to be designed (ii). In addition, cooperation with all parties should be well regulated (iii). The next important step is to analyse the target group of (potential) passengers, the stops and the bottlenecks and intersections (iv). Only after that is the system choice made (v). If a high-quality bus system is chosen, it needs to be designed (vi). Among other things, the route, the operation, the first/last mile transport and the branding have to be designed. When the design is ready, the line can be built, and operation can begin (vii). This can be done in stages, addressing the main bottlenecks first and the rest later. This is followed by the often overlooked evaluation, which is important for learning lessons for future projects.
Stakeholder feedback and a case study show the value of the roadmap for implementation in the Netherlands. By choosing the modality later in the process, compromises in quality are avoided. In addition, the in-depth analyses improve the quality of the line and enable faster implementation by identifying the main bottlenecks. The main value of the roadmap lies in its integral approach, rather than an approach from one perspective. This means that the problems of all stakeholders can be addressed to design a high-quality public transport system that works for all.
Choice modelling for planned special events
A study on improving accessibility of the AFAS AZ Stadium
To find the effectiveness of the obtained accessibility measures a stated preference study is held. From this study it is obtained that the transportation mode habit that one has is a key factor within the mode choice. Besides the effect on accessibility additional decision factors are discussed to find the best measure which can be applied best at the AFAS AZ Stadium. Based on the decision factors and the performance of the accessibility measures a total of six effective measures are determined. ...
To find the effectiveness of the obtained accessibility measures a stated preference study is held. From this study it is obtained that the transportation mode habit that one has is a key factor within the mode choice. Besides the effect on accessibility additional decision factors are discussed to find the best measure which can be applied best at the AFAS AZ Stadium. Based on the decision factors and the performance of the accessibility measures a total of six effective measures are determined.
Machine learning is utilized for abnormal driving behaviour detection because it offers a data-driven approach that adapts to different scenarios and captures subtle patterns. Furthermore, its scalability allows for efficient analysis of large datasets, leading to accurate identification of abnormal driving behaviour and valuable insights for enhancing road safety measures. Most existing machine learning (ML) based abnormal driving detectors rely on (fully) supervised ML methods, which require substantial labelled data. However, in the real world, labels are only sometimes available, and labelling large amounts of data is tedious. Thus, there is a need to employ unsupervised or semi-supervised methods to make the detection process more feasible and efficient. Luckily, it is possible with the advent of deep neural networks, especially autoencoder-based ones. This thesis develops and compares three ML methods: supervised (e.g. XGBoost and Random Forest), unsupervised ML (e.g. Isolation Forest and Robust Covariance), and semi-supervised ML (Hierarchical Extreme Learning Machines). Comparison results show that the semi-supervised deep learning model outperforms unsupervised methods exhibiting higher prediction accuracy and delivering acceptable results compared to the fully supervised models.
Moreover, previous ML-based approaches predominantly utilize basic car motion features (such as velocity and acceleration) to label and predict abnormal driving behaviours. In contrast, this thesis introduces Surrogate Measures of Safety (SMOS) as features for ML models to identify abnormal driving behaviour.
The results indicate that the supervised model performs best under the same conditions. However, relying on a large amount of labelled data in supervised models can pose challenges in real-life scenarios or when dealing with massive datasets. The study highlights the significance of Surrogate Measures of Safety (SMOS) and demonstrates the potential of HELM in effectively identifying abnormal driving behaviour. The introduction of SMOS significantly improves the performance of both unsupervised and semi-supervised models. The unsupervised model shows the most substantial improvement, increasing accuracy from less than 50% to over 90%.
While the Isolation Forest and Robust Covariance models fail to detect abnormal driving behaviour without including SMOS, the semi-supervised HELM model exhibits promising results even without SMOS. However, further research is necessary to address limitations and enhance the findings. While valuable, the current dataset used in this study may only encompass some types of abnormal driving behaviour. Future research should incorporate a more diverse dataset that covers a broader range of abnormal driving behaviours. The analysis should include multiple SMOS features, such as Post Encroachment Time (PET), to comprehensively understand abnormal driving behaviour and improve safety measures. ...
Machine learning is utilized for abnormal driving behaviour detection because it offers a data-driven approach that adapts to different scenarios and captures subtle patterns. Furthermore, its scalability allows for efficient analysis of large datasets, leading to accurate identification of abnormal driving behaviour and valuable insights for enhancing road safety measures. Most existing machine learning (ML) based abnormal driving detectors rely on (fully) supervised ML methods, which require substantial labelled data. However, in the real world, labels are only sometimes available, and labelling large amounts of data is tedious. Thus, there is a need to employ unsupervised or semi-supervised methods to make the detection process more feasible and efficient. Luckily, it is possible with the advent of deep neural networks, especially autoencoder-based ones. This thesis develops and compares three ML methods: supervised (e.g. XGBoost and Random Forest), unsupervised ML (e.g. Isolation Forest and Robust Covariance), and semi-supervised ML (Hierarchical Extreme Learning Machines). Comparison results show that the semi-supervised deep learning model outperforms unsupervised methods exhibiting higher prediction accuracy and delivering acceptable results compared to the fully supervised models.
Moreover, previous ML-based approaches predominantly utilize basic car motion features (such as velocity and acceleration) to label and predict abnormal driving behaviours. In contrast, this thesis introduces Surrogate Measures of Safety (SMOS) as features for ML models to identify abnormal driving behaviour.
The results indicate that the supervised model performs best under the same conditions. However, relying on a large amount of labelled data in supervised models can pose challenges in real-life scenarios or when dealing with massive datasets. The study highlights the significance of Surrogate Measures of Safety (SMOS) and demonstrates the potential of HELM in effectively identifying abnormal driving behaviour. The introduction of SMOS significantly improves the performance of both unsupervised and semi-supervised models. The unsupervised model shows the most substantial improvement, increasing accuracy from less than 50% to over 90%.
While the Isolation Forest and Robust Covariance models fail to detect abnormal driving behaviour without including SMOS, the semi-supervised HELM model exhibits promising results even without SMOS. However, further research is necessary to address limitations and enhance the findings. While valuable, the current dataset used in this study may only encompass some types of abnormal driving behaviour. Future research should incorporate a more diverse dataset that covers a broader range of abnormal driving behaviours. The analysis should include multiple SMOS features, such as Post Encroachment Time (PET), to comprehensively understand abnormal driving behaviour and improve safety measures.
Job (in)accessibility in the Parkstad region
About the impact of transport affordability on accessibility for low-income households and the unemployed
poverty and accessibility, with several publications discussing the need for accessibility standards to indicate injustice in the transportation system. Numerous case studies can be found where accessibility has been measured and assessed for fairness in the transport system, assuming that low-income households rely on public transport. This research reveals that up to now, the accessibility by public transport for low-income households and the unemployed is overestimated. Transport costs do not only have a diminishing effect on the accessibility by car, but also limits the accessibility by public transport. By means of the methodology ’Designing fair transportation systems’ it was possible to evaluate the job accessibility in the Parkstad region, a region where income on average is the lowest in the Netherlands and the unemployment rates the highest. The limited job accessibility by both car and public transport raises the question to what extent transport poverty contributes to the high unemployment rates in this region. Municipalities are recommended to use these results to further explore what the population groups suffering from transport poverty need and propose interventions to improve job accessibility for those who need this the most.
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poverty and accessibility, with several publications discussing the need for accessibility standards to indicate injustice in the transportation system. Numerous case studies can be found where accessibility has been measured and assessed for fairness in the transport system, assuming that low-income households rely on public transport. This research reveals that up to now, the accessibility by public transport for low-income households and the unemployed is overestimated. Transport costs do not only have a diminishing effect on the accessibility by car, but also limits the accessibility by public transport. By means of the methodology ’Designing fair transportation systems’ it was possible to evaluate the job accessibility in the Parkstad region, a region where income on average is the lowest in the Netherlands and the unemployment rates the highest. The limited job accessibility by both car and public transport raises the question to what extent transport poverty contributes to the high unemployment rates in this region. Municipalities are recommended to use these results to further explore what the population groups suffering from transport poverty need and propose interventions to improve job accessibility for those who need this the most.
Understanding the commuters' choice for HOV bus services in the Netherlands
Understanding the commuters’ choice for HOV bus services in regards to the regular bus in the Netherlands
Visibility of Lane Markings for Machine Vision
Assessment of Lane Detection Performance based on Different Lane Marking Properties under Optimal and Adverse Weather and Lighting Conditions
Coverage Practices in a Patronage Based Bus Network Design Process
A Case Study on Zuid-Holland Noord, the Netherlands
developed in order to compare four different network designs relying on various coverage practices. The results show that a two layered system consisting of a high quality service combined with a supporting service in the form of a regular and/or demand responsive service is the best approach. Within the existing cost constraints, it is possible to create a large high quality network that relies on bicycles as access mode. By including shared bicycles, the coverage function is ensured while increasing the cost-efficiency of the network by allowing for faster routing. As a result, 10 percent more trips were made per timetable hour and 3 percent more passenger kilometres were covered. Replacing regular fixed line services by demand responsive services resulting in only a marginal increase that was highly dependent on the costs not to turn out higher. In combination with bicycle sharing, the results turned out to be much more positive with an additional 11 percent increase. By using a two layered system a high quality service can be provided that also serves a large coverage function. Of the supporting services, the use of shared bicycles allow for opportunities to improve even further, especially when combined with demand responsive transport. ...
developed in order to compare four different network designs relying on various coverage practices. The results show that a two layered system consisting of a high quality service combined with a supporting service in the form of a regular and/or demand responsive service is the best approach. Within the existing cost constraints, it is possible to create a large high quality network that relies on bicycles as access mode. By including shared bicycles, the coverage function is ensured while increasing the cost-efficiency of the network by allowing for faster routing. As a result, 10 percent more trips were made per timetable hour and 3 percent more passenger kilometres were covered. Replacing regular fixed line services by demand responsive services resulting in only a marginal increase that was highly dependent on the costs not to turn out higher. In combination with bicycle sharing, the results turned out to be much more positive with an additional 11 percent increase. By using a two layered system a high quality service can be provided that also serves a large coverage function. Of the supporting services, the use of shared bicycles allow for opportunities to improve even further, especially when combined with demand responsive transport.