Poster presentations highlighting recent research in the field of transportation noise.
Probabilistic Evaluation and Component Modeling of Sound Absorption Coefficient of Pervious and Non-Pervious Pavements at the MnROAD Research Facility
Bernard Izevbekhai, Minnesota Department of TransportationShow Abstract
Annika Christiansen, Minnesota Department of Transportation
If pavement surfaces are sound absorbent they may be used to reduce height and cost of noise walls. Sound Absorption Coefficient measures the ratio of sound energy absorbed by a pavement to the total sound energy incident on that pavement surface. This property is proxy for important pavement properties over time. In-place pavement sound absorption tests were conducted with an impedance tube equipped with a white noise source and an analyzer, on various pavement types (Cells 32, 39, 85, 86, 87, 88, and 89 at the MnROAD Low Volume Road) from 2009 to 2014. These cells represent non-pervious concrete, pervious concrete overlay, pervious concrete on granular base, pervious asphalt on granular base, non-pervious asphalt, pervious asphalt on cohesive base, and pervious concrete on cohesive base, respectively. Probabilistic analysis of Sound Absorption at 1000 Hz frequency data showed that the non-pervious pavements had significantly lower values than the pervious pavements. The non-pervious concrete pavements exhibited significantly lower sound absorptions in comparison to the non-pervious asphalt counterparts. Pervious asphalt and non-pervious concrete exhibited the highest and lowest sound absorption coefficient respectively. Unlike the corresponding pervious asphalt cells, pervious concrete pavements built on granular subgrade exhibited higher sound absorption than corresponding pervious pavements on cohesive subgrades. Prediction model developed in this study and validated by the Sound Absorption data showed that traffic (loaded versus unloaded lane) as well as age after construction reduced sound absorption coefficient whereas porosity and viscoelasticity exhibited strong sound absorption enhancing variables.
TNM Sub-Source Height Analysis - TNM-Defined Heavy Truck Vs. User-Defined Heavy Truck
Eric Moskus, ICF International IncShow Abstract
Peter Hardie, ICF International Inc
The use of the TNM 2.5 to predict traffic noise levels and design traffic noise abatement in the form of noise barriers is influenced by the sub-source heights for heavy trucks, with sound energy emissions at 0 feet and 12 feet above ground level. Recent field measurement studies indicate that the upper (12 feet) sub-source may be overestimating the height of the sound energy from heavy trucks. Therefore, an alternative modeling methodology that reduces the height of the upper sub-source height of heavy truck sound energy is investigated. A user-defined vehicle type that contains the noise energy of a heavy truck but divides the energy between the lower sub-source heights of a medium truck (i.e., 0 and 5 feet) may result in better TNM model validation results and increased insertion loss values for designed noise barriers, specifically at shorter barriers. This paper describes the influence this modeling methodology has on both TNM model validation and barrier analysis results in real-world and hypothetical models.
Analysis and MASH TL-5 Crash Testing of a 6 foot Tall Constant Slope Barrier with Attached Noise Abatement Wall
Akram Abu-Odeh, Texas A&M Transportation InstituteShow Abstract
Ahmad Hammad, WSP
Transportation agencies have become more efficient in maximizing the utilization of the roadway space due to financial and regularity constraints. Safety must manifest itself in all the aspects of the transportation infrastructure. One notable challenge is the use of high speed highways within urban environments. A noise reduction facility such as a Noise Abatement Wall (NAW) has to be incorporated along the roadway to reduce the traffic generated noise impact on the urban population. However, adding such a NAW requires a minimum of four feet offset from the barrier per existing guidelines from American Association of State Highway Transportation Officials (AASHTO) standards. These constraints are eliminated in this study by designing a tall barrier and reducing the interaction of the leaning trailer with the NAW to insignificant rubbing. This paper presents the design of the barrier-NAW system, the finite element simulation that verified the performance of the system and the successful outcome of the full-scale crash testing according to AASHTO Manual for Assessing Safety Hardware MASH guidelines.
Agent-Based Simulation of City-Wide Autonomous Ride-Pooling and the Impact on Traffic Noise
Felix Zwick (email@example.com), Swiss Federal Institute of Technology (ETH Zurich)Show Abstract
Nico Kuehnel, Technical University of Munich
Rolf Moeckel, Technische Universitat Munchen
Kay Axhausen, Eidgenossische Technische Hochschule Zurich
Pooled on-demand mobility provides an efficient way of using public road infrastructure by bundling multiple trip requests. It promises to provide convenient transportation and to reduce negative externalities of road transport. Previous studies have shown the positive effects of ride-pooling in regards to reduced fleet sizes and vehicle kilometers travelled. We apply an established ride-pooling algorithm within the simulation framework MATSim to an autonomous fleet serving a synthetic population of Munich in a 200 km2 service area. We implemented one scenario with a policy substituting all car trips in the service area by the ride-pooling system, leading to almost 2 million rides. In another scenario all agents are free to use the new means of transport and mode choice is based on an existing mode choice model. For both policies, a stop-based and a door-to-door service is implemented. We compare the scenarios in terms of system efficiency and noise emissions, applying a noise emission model that we improved and adapted to a new noise guideline in MATSim. Results indicate that vehicle kilometers travelled decrease by over 50 % for the stop-based system if all car trips are replaced. Noise exposure is drastically reduced in residential areas with low stop density. In the door-to-door case, noise exposure in residential areas can even increase due to additional cruising for pick-up and drop-off purposes. As agents from all modes switch to ride-pooling in the scenario with free mode choice, noise exposure is generally increased, but can be locally regulated through the stop network.
Pavement Acoustic Mapping Technology Demonstration Project
Bruce Rymer, California Department of Transportation (CALTRANS)Show Abstract
Paul Donavan, Illingworth and Rodkin, Inc.
Carrie Janello, Illingworth & Rodkin, Inc.
David Buehler, ICF International Inc
Traffic noise is a constant environmental concern of the public. Pavement is the primary product for State Departments of Transportation and tire/pavement noise is the primary noise source for most vehicles operating at cruising freeway speed. Extensive California experience and research has found that, a change in pavement acoustics generates a similar change in roadside noise levels. Pavement acoustics impact roadside noise levels in a predictable, quantifiable, and measurable way − most the time. ‘Quieter’ pavements can be an effective solution and tool for mitigating highway noise impacts and addressing noise complaints. Building on National Academy of Science /NCHRP OBSI research, Caltrans paired short-interval tire/pavement acoustic measurements, using the AASHTO T-360 OBSI Tire/Pavement Measurement Standard, with global position system (GPS) coordinates and then mapped this data on a geographic information system (GIS) webserver. The GIS webserver was setup to allow all the stake holding transportation agencies access to view and use the acoustic information. The GIS data shows sound level and location relative to roadside neighborhoods. This measurement procedure allows a much more systematic approach to addressing corridor-wide noise complaints and provides an objective process to rank order pavement rehabilitation projects that would reduce noise levels in roadside neighborhoods. From this new measurement approach, it is possible to accurately estimate roadside community noise levels due to the highway, with much more precision. This approach provides a much-needed tool for SDOTs to address noise complaints and concerns much more effectively.
A Before-and-After Traffic Noise Analysis of a Roundabout Converted to a Signalized Intersection in Qatar
Khaled Shaaban (firstname.lastname@example.org), Utah Valley UniversityShow Abstract
Khadija Abdur-Rouf, Qatar University
Many public agencies have undertaken initiatives to convert from one intersection type to another to address issues of safety, operation, and efficiency. However, the contribution of an intersection type towards environmental noise pollution in an urban environment should be considered during such decision-making. Accordingly, studies have analyzed noise level contributions of various intersection types using simulations. Nevertheless, there is a need for before-and-after noise level studies to be conducted using field measurements at the same intersection so that site factors and traffic conditions, except for the intersection type, remain the same. Consequently, this paper aims to conduct such a study at an intersection before and after being converted from a roundabout to a signalized intersection. 64 hours of traffic noise level, weather, and traffic data were collected and analyzed. The resulting mean traffic noise levels on weekday and weekend corresponding to the mean traffic volumes at the signal exceeded the roundabout by 3.5 and 3.7 dB(A) due to 8% (207 vehicles) and 23% (279 vehicles) more traffic volume at the signal, respectively. Hence, the signal generated more traffic noise than the roundabout on both weekday and weekend. This information can be useful for public agencies, policymakers, and practitioners when making decisions to convert roundabouts to signals and vice versa.
A Traffic Noise Prediction Study in Doha, Qatar: Modification of the CORTN Model for Roundabouts and Signalized Intersections
Khadija Abdur-Rouf, Qatar UniversityShow Abstract
Khaled Shaaban (email@example.com), Utah Valley University
In this paper, the development of general and intersection type-specific traffic noise prediction models calibrated for Doha, the capital and the busiest city of Qatar, is presented as a case study. The newly proposed models are based on 172 hourly traffic noise level (L Aeq.1hr. ) , corresponding hourly traffic volume, and other site data collected at eight 2-lane and 3-lane roundabouts and signalized intersections in the city. Thus, the main objective is to develop traffic noise prediction models appropriate for the unique geographic, socio-economic, and traffic features of Qatar and other similar regions to investigate whether intersection type-specific models are better than calibrated general models. Based on the customized and modified Calculation of the Road Traffic Noise (CORTN) prediction models, the intersection type-specific CORTN models fitted the measured data at the four different intersections types better than the general original and modified CORTN models, reducing the RMSE from 10.3 dB(A) to 0.7 dB(A). Besides, the calibrated models could also be used to determine whether traffic noise levels at different traffic intersections in Doha is within the World Health Organization’s acceptable daytime noise level threshold of 65 dB(A). Hence, the customized models are expected to be advantageous in terms of predicting traffic noise levels at 2-lane and 3-lane roundabouts and signals in Doha and other similar cities so that governments, policy makers, traffic engineers, and urban planners can implement necessary noise management and mitigation strategies.
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