Konstantinos Vogiatzis

On the outdoor annoyance from scooter and motorbike noise in the urban environment

The health impacts of environmental noise are a growing concern amongst both the general public and policy-makers in Europe. Environmental noise - especially from road transportation - is widely accepted as an important environmental impact factor that can be taken as a start for the process of evaluating the impact of annoyance on the exposed urban population. Extensive urbanisation and the increase of road transport define the main driving forces for the environmental noise exposure of the population. In urban conditions, it is rather common, regarding road transportation noise, to hear from people that, especially, PTW (Powered Two Wheelers) are annoying, and many times are actually the most annoying environmental noise sources introducing a degradation of the urban environment. In this research, in Athens city centre, both scooters and motorbikes operation patterns are analysed, in the basis of their environmental impact through ad-hoc tests to establish if specific features of their emitted noise are annoying and affect the quality of life. It resulted that PTW are a relevant cause of specific environmental annoyance on pedestrians when low background noise levels and sparse traffic flow allow identifying the PTW. Based on the results of a measurement campaign, both L(max) and roughness indices are identified as characteristic noise signatures of the PTW. Results are compared to laboratory studies on annoyance found in literature and to a specific set of interviews with a large number of pedestrians in selected sites. Annoyance caused by scooters and motorbikes is analysed in the findings and conclusions.

Railway ground vibrations induced by wheel and rail singular defects

Railway local irregularities are a growing source of ground-borne vibration and can cause negative environmental impacts, particularly in urban areas. Therefore, this paper analyses the effect of railway track singular defects (discontinuities) on ground vibration generation and propagation. A vehicle/track/soil numerical railway model is presented, capable of accurately predicting vibration levels. The prediction model is composed of a multibody vehicle model, a flexible track model and a finite/infinite element soil model. Firstly, analysis is undertaken to assess the ability of wheel/rail contact models to accurately simulate the force generation at the wheel/rail contact, in the presence of a singular defect. It is found that, although linear contact models are sufficient for modelling ground vibration on smooth tracks, when singular defects are present higher accuracy wheel/rail models are required. Furthermore, it is found that the variation in wheel/rail force during the singular defect contact depends on the track flexibility, and thus requires a fully coupled vehicle/track/foundation model. Next, a parametric study of ground vibrations generated by singular rail and wheel defects is undertaken. Six shapes of discontinuity are modelled, representing various defect types such as transition zones, switches, crossings, rail joints and wheel flats. The vehicle is modelled as an AM96 train set and it is found that ground vibration levels are highly sensitive to defect height, length and shape.

Prediction and efficient control of vibration mitigation using floating slabs: practical application at Athens metro lines 2 and 3

This paper describes the finite element modelling and the in situ evaluation of anti-vibration mitigation measures recently introduced in the latest two extensions on lines 2 and 3 of the Athens Metro: (1) extension of Line 3 from Aigaleo to Haidari and (2) extension of Line 2 from Agios Antonios to Anthoupoli. Appropriate mitigation measures, guaranteeing the allowable ground-borne noise and vibration levels, especially in crossover (CO) locations, were examined, within a noise and vibration study. To do this, the alignment was divided into homogeneous sections, i.e. sections along which the tunnel and soil types, depth and distance from nearby buildings, with particular emphasis on section with COs on direct fixation. Floating slab (FS) track solutions were then evaluated at COs locations ensuring a complete ground-borne vibration attenuation with an insertion loss of −20 dBV with respect to the predominant excitation (40–125 Hz). The relevant in situ measurement campaign regarding both the dynamic characteristics of FS and the vibration velocity at the relevant receptors proves that the ground-borne noise in the nearest – to FS – buildings at all CO locations was significantly lower than the maximum allowable limits proving the high efficiency of the mitigation measure.

Modelling the Environmental Effects of Railway Vibrations from Different Types of Rolling Stock: A Numerical Study

This paper analyses the influence of rolling stock dynamics on ground-borne vibration levels. Four vehicle types (Thalys, German ICE, Eurostar, and Belgian freight trains) are investigated using a multibody approach. First, a numerical model is constructed using a flexible track on which the vehicles traverse at constant speed. A two-step approach is used to simulate ground wave propagation which is analysed at various distances from the track. This approach offers a new insight because the train and track are fully coupled. Therefore rail unevenness or other irregularity on the rail/wheel surface can be accurately modelled. Vehicle speed is analysed and the frequency spectrums of track and soil responses are also assessed to investigate different excitation mechanisms, such as carriage periodicities. To efficiently quantify train effects, a new (normalised) metric, defined as the ratio between the peak particle velocity and the nominal axle load, is introduced for a comparison of dynamic excitation. It is concluded that rolling stock dynamics have a significant influence on the free field vibrations at low frequencies, whereas high frequencies are dominated by the presence of track unevenness.

Noise reduction in urban LRT networks by combining track based solutions.

The overall objective of the Quiet-Track project is to provide step-changing track based noise mitigation and maintenance schemes for railway rolling noise in LRT (Light Rail Transit) networks. WP 4 in particular focuses on the combination of existing track based solutions to yield a global performance of at least 6dB(A). The validation was carried out using a track section in the network of Athens Metro Line 1 with an existing outside concrete slab track (RHEDA track) where high airborne rolling noise was observed. The procedure for the selection of mitigation measures is based on numerical simulations, combining WRNOISE and IMMI software tools for noise prediction with experimental determination of the required track and vehicle parameters (e.g., rail and wheel roughness). The availability of a detailed rolling noise calculation procedure allows for detailed designing of measures and of ranking individual measures. It achieves this by including the modelling of the wheel/rail source intensity and of the noise propagation with the ability to evaluate the effect of modifications at source level (e.g., grinding, rail dampers, wheel dampers, change in resiliency of wheels and/or rail fixation) and of modifications in the propagation path (absorption at the track base, noise barriers, screening). A relevant combination of existing solutions was selected in the function of the simulation results. Three distinct existing solutions were designed in detail aiming at a high rolling noise attenuation and not affecting the normal operation of the metro system: Action 1: implementation of sound absorbing precast elements (panel type) on the track bed, Action 2: implementation of an absorbing noise barrier with a height of 1.10-1.20m above rail level, and Action 3: installation of rail dampers. The selected solutions were implemented on site and the global performance was measured step by step for comparison with simulations.

Soundscape design guidelines through noise mapping methodologies: An application to medium urban agglomerations

Abstract In the framework of the European Directive 2002/49/EC, from 2012 to 2016, several cities in Greece have completed noise strategic maps with noise action plans that usually define the main strategies to reduce the noise residents are exposed to and introduce and preserve “quiet zones”. Several medium urban agglomerations in Greece (Volos, Larissa, Chania, Heraklion, Corfu, Agrinio, Thessaloniki) have been chosen to also analyse the sound qualities of the soundscapes of specific urban neighbourhoods in order to generate recommendations for the urban design of the soundscapes of these agglomerations in a manner that complements conventional noise mitigation measures. The general principle of this approach is to relate quantitative data (e.g., from measurements, acoustic simulations, urban forms, topography, and traffic model) with qualitative data (e.g., from type of sources, interviews, reports on environmental noise perception) by creating quantitative and qualitative maps. The aim of this study is to propose possible action tools to the relevant authorities aiming at diminishing noise levels in affected areas and also to provide solutions towards a sustainable sound environment both in space and time. This paper presents the main current methodology, selected important results proposed for the urban agglomerations of a typical Southeast Mediterranean country such as Greece.

Ground-borne noise and vibration transmitted from subway networks to multi-storey reinforced concrete buildings

During the operation of urban subway rail transit systems, vibrations are generated that transmitted through the soil, induce vibrations in nearby buildings. The transmission of ground-borne vibrations from subway rail transit systems in a building is governed by the soil-foundation interaction, the reduction of vibration level between floors, and the amplication due to resonances of building elements. These are influenced by the type of the building, its construction materials, the foundation soil, and the frequency content of the excitation. A methodology is proposed for the determination of the sound vibration along the height of the building for a specic construction type, demonstrating how the attenuation and amplication parameters can be calculated. For this particular building type, a notable amplication of the vibration due to floor and other structural resonances was found, whereas the vibration and hence the radiated noise levels are similar from the first floor up. An overall building amplication factor is proposed, taking into account all the above mentioned transmission mechanisms. First published online 04 September 2017

Assessment of railway ground vibration in urban area using in-situ transfer mobilities and simulated vehicle-track interaction

ABSTRACT This article proposes an alternative approach to the well-known Federal Railroad Administration method to evaluate ground vibrations induced by the passing of railway vehicles. The originality lies on the excitation mechanisms that occur in urban areas. A common source of railway-induced ground vibrations is local defects (rail joints, switches, and turnouts) which cause large amplitude excitations at isolated locations along the track. To analyse such situations, a combined numerical-experimental study is developed, based on the use of numerical train/track results and experimental mobility transfer functions. The influence of building foundation type, vehicle, defect type, and size and location is evaluated through experimental data collected in Brussels (Belgium). The results show that it is possible to assess vibrations from light rapid transit systems in the presence of local rail defects and unknown soil conditions.

Noise score rating models for Q-Zones andembedded parks

Abstract CITYHUSH project supports city administrations in the implementation of noise action plans according to the EU directive 2002/49/EC. The action “Noise and vibration control at source – Acoustically green vehicles” validates noise score rating models in a case in the Athens area, including Q-Zones (Quiet zones) and embedded parks, identifying perceived benefits on noise. Annoyance for PTW (powered two-wheeler) is masked in general traffic annoyance. However, a PTW pass may become recognizable and clearly distinct within the traffic noise environment formed by the road traffic flow and synthesis. Several strategic noise mapping scenarios with high noise levels from PTWs, as well as low frequency noise annoyance events, were evaluated proving that the noise levels in a Q-Zone and embedded parks may be reduced with an increased park capacity. Measures with a special focus on the reduction of conventionally powered motorbikes and scooters (PTWs) were evaluated. PTW’s emission values were derived, from known values and past measurements, in the form of a correction function as a function of speed to perform simulation analysis for various analogies of conventionally versus electrically driven PTWs. Relevant noise difference maps indicate noise reductions, especially when additional measures are included, such as speed limits.

Monitoring and assessing the effects from Metro networks construction on the urban acoustic environment: The Athens Metro Line 3 Extension

The Line 3 Extension from Aghia Marina to Piraeus constitutes one of the most significant construction projects in full development in Athens Greater area. For the management and abatement of the air borne noise generated from surface, and/or underground construction activities, relevant machinery operation, and trucks movements at open worksites and the tunnel, a continuous monthly noise and vibration monitoring program is enforced in order to assess any potential intrusion of the acoustic environment. On basis of measured 24 hour Leq noise levels, both Lden and Lnight EU indices were assessed along with vibration velocity for every worksite and tunnel construction activity. The existing environmental noise background generated mainly from road traffic was assessed in order to evaluate potential effects on both air borne noise from construction activities. This comprehensive monitoring program aims to protect the inhabitants in the vicinity of worksites and the tunnel surrounding from construction noise and vibration processing and evaluating all necessary mitigation measures. Especially, for the protection of sensitive receptors, this program may serve as a tool ensuring a successful management of both noise and vibration levels emitted from open air construction activities and (Tunnel Boring Machine) TBM or hammer/pilling operation by implementing mitigation measures where necessary.