GAZEX avalanche control system noise & vibration study
Time: 12:00 pm
Author: Paul Bollard
Abstract ID: 1468
Bollard Acoustical Consultants, Inc. was retained by the Placer County Planning Dept. to quantify noise and vibration levels resulting from the Gazex avalanche control system usage during the winter of 2018-2019. The primary objective of the monitoring program was to obtain a statistically representative sample of noise and vibration data during Gazex usage for comparison against criteria for potential damage to structures and human hearing. During the survey period, 75 discrete discharges of Gazex cannons occurred. Each discharge was monitored at five fixed monitoring sites in the Alpine Meadows residential community. At the completion of the survey, 1,079 of the possible 1,125 possible data points of interest had successfully been captured. The results of the surveys indicated that, although noise and vibration levels generated by the Gazex system were elevated to the point of being considered highly annoying to local residents, criteria for damage to hearing and structures were not exceeded during the survey period.
Relation between soundscape and spatial configuration in different urban contexts
Time: 12:40 pm
Author: Giacomo Salvadori
Abstract ID: 1834
During the last decade, the problem of noise pollution has continued to increase in Europe as well as in under-developed countries. This issue is stressed in city centers, owing to the abundance of residential activities, vehicle traffic and multiple services. This study investigates the relationship between urban spatial configuration and environment soundscape in two different areas: Pisa historic center, Italy and Biskra downtown, Algeria, using the potential of Space Syntax theory in predicting noise levels distribution. For this analysis, thirty stations of measurements were held in each area during day time using a Sound Level Meter. A Noise map was modeled using the interpolation tool provided by a Geographic Information System program, while the collected data were correlated with the Angular Segment Analysis variables. The findings reveal a close relationship between the sound levels obtained and Space Syntax theory global and local indexes such as Normalized Choice and Integration, which signifies the ability of the approach in describing the sound phenomenon in different urban contexts.
Montevideo, walkable city: pedestrianization of a large avenue during 2020 pandemic
Time: 12:40 pm
Author: Alice Elizabeth Gonzalez
Abstract ID: 1878
On March 13, 2020, the first cases of SARS-COVID19 were detected in Uruguay. During the first weeks of the pandemic, mobility was significantly reduced with the slogan "If you can, stay home; it was not a mandatory but voluntary confinement. After a couple of months, there was a big drop in the number of people affected by the disease. Thus, the Municipality of Montevideo, betting on a more human and walkable city, defined that the main avenue of the city had a pedestrian section on Saturday afternoons. This resulted in a greater enjoyment of the city by its inhabitants, as they had more space to walk while maintaining safe distances between people. It was also possible to promote trading, since classically Ave. 18 de Julio is also a commercial stroll. Additionally, the sound pressure levels recorded by the Municipality's stationary sound level meters located at three points along the avenue, showed the reduction of environmental sound levels in pedestrian areas, improving the acoustic quality of the walk. In this paper, sound pressure levels on Saturday afternoons at different times of the year before, during and after the initial lockdown due to the COVID-19 pandemic, are compared and discussed.
Noise codes and acoustical design criteria for distribution facilities
Time: 12:20 pm
Author: Michael Conaway
Abstract ID: 1880
Distribution and warehouse-type facilities are routinely constructed all over the country and the world. On-site noise sources for this type of facility include heavy trucks, delivery vehicles, and rooftop HVAC equipment. Stationary noise is often more clearly regulated than mobile noise sources. To protect the public, appropriate criteria need to be established for all sources. Some jurisdictions have quantitative regulatory limits in place that may be used as design criteria while others may have less helpful qualitative code language or no noise code at all. A review of common metrics found throughout the U.S. is presented to understand code language that appropriately protects the public for specific sources. In addition, it is useful to analyze and discuss common criteria applied in the absence of quantitative code limits.
Air-cooled chiller screening noise analysis with preliminary building project information
Time: 1:40 pm
Author: Mark Storm
Abstract ID: 2939
For Inter-noise 2018, the author submitted a paper proposing techniques to derive reasonable preliminary estimates of building project stationary noise emission levels from sparse but available data that may seem unrelated to noise or vibration such as gross square footage (GSF), expected occupancy, and land use or function. Results from these predictions would be used to support or refine established buffer distances between exposed outdoor heating, ventilating, and air-conditioning (HVAC) system noise sources and nearby noise-sensitive receptors, helping planners tasked with ambitious infill or growth goals better fit building projects into complicated campus development puzzles. This paper provides supplemental guidance by linking the same preliminary building project GSF, occupancy, and function information to estimates of cooling load (expressed as refrigeration tonnage) and thus an additional HVAC consideration not discussed in the authors previous study. When such refrigeration relies upon air-cooled condensers installed outdoors on building rooftops or at grade, substantial noise sources are introduced to the environment. Thus, this new study shares data and methodology to help expand the value and utility of the previous work and potentially provide more comprehensive building HVAC noise estimates for use by building developers and planners.
Design of noise barriers for the mitigation of construction noise
Time: 11:00 am
Author: Heow Pueh Lee
Abstract ID: 1628
Noise pollution is a major problem in many major cities in particular a small island state like Singapore with residential buildings very close to the major trunk roads and expressways. The problem is aggravated by the ongoing city redevelopment and construction of new mass rapid transit lines. Construction noise is therefore a common theme of public complaints and therefore there is an increased interest in the development of more effective mitigation measure for construction noise. In this work, a Flat-tip jagged-edge profile was investigated and applied on the edge of a cantilever (slanted up for 45 degrees, facing the noise source) which was mounted at the top of a passive noise barrier. Besides the numerical simulations, the full sized prototypes were also experimentally tested on a construction sites with noise generated by a boring machine. Both numerical simulations and experimental results showed that this barrier with a slanted Flat-tip jagged cantilever would perform better than the traditional barrier having a Straight-edge cantilever of same height, with a maximum additional attenuation of 5.0 dBA experimentally obtained. The barrier with slanted Flat-tip jagged cantilever could also extend the shadow zone behind the barrier to higher levels of the building.
Modelling the variability of noise from construction sites using Monte-Carlo analysis
Time: 11:40 am
Author: Dave Davis
Abstract ID: 1826
Noise emissions from construction sites are inherently unsteady. Noise emissions vary due to many causes, including the noise sources frequently changing in location, orientation, the types of activities they perform, and the acoustic shielding due to structures and/or terrain. The noise that arrives at receivers from construction site equipment can fluctuate over all time scales, from seconds to hours, days, months or years. Prediction of noise levels typically assumes either a worst-case approach in which all noise sources are assumed to be operating simultaneously, or by predicting an energy-average (Leq) level over a long time period. In the latter case, an energy-average (Leq) noise level is predicted at receivers, based on the anticipated percentage utilisation of the various noise sources on the construction site that is, the fraction of time that each item of equipment is operating or not during the averaging time period. This paper presents a method that may be used to estimate the variability of noise emissions from the site and the corresponding noise immissions at receivers using the Monte-Carlo simulation method. Using this method, the expected minimum, maximum, percentiles and energy-average (Leq) noise immission levels at receivers can be predicted.
Construction Noise Management in Hong Kong – Now and Beyond
Time: 11:20 am
Author: Wilson Ho
Abstract ID: 3142
Hong Kong is a mature and busy metropolis with 7.5 million residents. Being constrained by limited land area for development, the cityscape of Hong Kong is primarily 3-dimensional in nature. The vast majority of the growing population is accommodated in closely packed high-rise residential towers. Similar to other major urban centres worldwide, Hong Kong citizens are affected by the virtually continuous construction activities expanding and renewing the city. The numerous construction sites are also bringing noise disturbance to some neighbourhoods. In 2020, the Hong Kong Environmental Protection Department completed a feasibility study on managing construction noise, including those associated with renovation of domestic premises. Part of the study was the conducting of face-to-face interviews of more than 5,000 households via a large scale public survey to gauge their views on construction noise disturbance, among others. This paper describes the current state and conditions of construction noise in Hong Kong, the issues and constraints, as well as challenges and opportunities. Highlights from the scientifically conducted public survey will be included to provide a robust and more comprehensive description of the prevailing situation.