Noise emissions from sustainable transport : A multi-scale modeling approach

Abstract: Noise emissions from transportation remain one of the greatest environmental issues of modern day. Inhabitants in urban environments are especially exposed, with almost 80 million people in the European Union exposed to noise levels exceeding the recommended limits set by the World Health Organization (WHO). The community engaged in the research field of environmental acoustics is in agreement: the exposure to road traffic noise must be reduced to the benefit of our health and well-being. While the health-related effects from exposure of traffic noise are problematic and of utmost importance to reduce, the provision of efficient transport is also a necessity. Therefore, innovative approaches and solutions are critical, e.g. in infrastructure, policies, legislation, or technological aspects of the vehicles, to sustainably fulfill the mobility needs of tomorrow. These conflicting requirements on transportation call for a more holistic approach to traffic analysis, and a better understanding of the relation between these effects from the traffic.This thesis introduces the noise exposure cost (NEC) methodology to evaluate the contributions from individual vehicles to the overall traffic noise impact in a systemic, multi-vehicle context. By integrating NEC with microscopic traffic simulations, the approach allows for feedback on the long-term noise exposure caused by specific vehicles at a micro-scale. Vehicle noise emissions result from both vehicle type characteristics and driving behavior, which can be assessed holistically. The work performed as part of this thesis emphasizes the trade-off between model scalability and fidelity in traffic simulations, noise prediction, and the evaluation of health and well-being impacts. It also explores the connection between models, highlighting dependencies on vehicle properties and kinematics. The research identifies the significant influence of acceleration on vehicle noise emissions, especially during peak urban traffic hours, impacting correlations between model outputs.Additionally, the concept of allocating the noise exposure cost down to individual vehicles by means of contributed acoustic energy is expanded to take the main contributing vehicles and time-segments into consideration, and to allow for a non-linear weighting factor. These allocation strategies also allow for more of the total NEC being allocated to more noisy vehicles, as vehicles that contribute more to the overall noise exposure than others may be more easily identified.In conclusion, the NEC methodology enables the assessment of systemic impact of noise exposure at a micro-scale resolution of the traffic, and may prove useful for holistic approaches to evaluate noise-related legislations and policies, as well as technological aspects of the vehicles.