Now Hear This! What All Environmental Engineers Should Know About Noise Control

Noise is an is an that affects almost everyone. And even though environmental engineers are often called on to deal with noise-related problems, most of them receive little or no academic training in noise control. This primer suggests why all environmental engineers should know something about noise control, what they need to know, and where they can find the necessary information

Landfill Noise

Noise studies were performed at a Florida landfill to determine sound pressure level footprints around landfills and to predict the noise impact of the landfill on surrounding areas. The study involved measurements of both landfill and incineration activities and the characterization of those noise sources. The majority of landfill activities involve heavy trucks and construction equipment, which results in large variations of source sound levels at the landfill. The heavy trucks and equipment operations were the dominant noise sources at the landfill. The maximum sound pressure levels are from equipment back up alarms. Measurements of the incinerator demonstrated that it had significantly lower sound levels than other typical landfill sources. The source-specific data was utilized to draw baseline source levels for typical equipment found at landfills and entered into a model used to predict landfill noise levels from equipment types and locations

Combined Noise Model For Hsgt Traffic

Environmental concerns are high on the list of possible problem areas for proposed high speed ground transportation (HSGT) systems. A Federal Highway Administration (FHWA) Highway Traffic Noise Prediction Model written in FORTRAN known as STAMINA 2.0 was developed in the early 1980\u27s to predict noise levels from roadway transportation sources. In anticipation of the need to model both high speed ground transportation and highway traffic on common right-of-ways, modifications were performed and implemented to a PC version of the STAMINA model. This paper describes this work which was done at the Department of Civil and Environmental Engineering at the University of Central Florida in Orlando, Florida. The information provided in this paper should be useful to any agency or firm interested in noise analysis and barrier design models used for HSGT and highway traffic

Advancement in traffic noise modeling: The AAMA community noise model 4.0

The University of Central Florida developed the AAMA Community Noise Model (CNM) which is a traffic simulation model that determines sound levels at receivers by modeling vehicles as discrete moving point sources. The vehicle energy is determined from acceleration, deceleration, idle and cruise reference energy mean emission level curves. Attenuation of energy from the vehicles for distance, ground adsorption and user input barriers is calculated. The model sums the energy at receivers on user defined time steps from all vehicles and then calculates the Leq noise level at the receivers

Railway Noise Model

The Railway Noise Model (RWNM) was developed at the Univ of Central Florida and predicts sound levels at receivers near railway operations for analyses used in environmental documents. The RWNM is a simulation model, and trains are modeled as moving point sources of sound. The user can create model objects, tracks, barriers, and receivers, using either the mouse or spreadsheet interfaces. During simulation, the user observes trains moving along railways and the relationships to receiver locations. The RWNM simulates a 24-h period of rail traffic and computes day/night sound pressure level (Ldn), maximum sound pressure level (Lmax), sound exposure level (SEL), and equivalent sound pressure level (Leq) at the receivers. The RWNM uses REMEL (reference energy mean emission levels) curves based on Federal Transit Administration (FTA) reported Lmax pass-by levels for locomotives and rail cars. In addition, the model has the ability to model heavy rail locomotives and rail cars, which makes it applicable to Federal Railroad Administration projects. Testing has shown that the RWNM results match those of the FTA-approved spreadsheet, although heavy rail validation is limited

Simulation approach to traffic noise modeling: American automobile manufacturers association community noise model version 4.0

Several models are available for predicting traffic noise levels. The FHWA-promulgated model, STAMINA 2.0, is the most widely used noise model in the United States and is used to model free-flow vehicular traffic. STAMINA 2.0 cannot directly model interrupted-flow traffic. Sound levels from interrupted-flow traffic can be approximated with STAMINA 2.0 using the method presented in NCHRP Report 311. This method is time-consuming and difficult to use. These limitations demonstrate the need for a traffic noise model that can model the acceleration and deceleration behavior of interrupted-flow traffic. The University of Central Florida has developed the American Automobile Manufacturers Association Community Noise Model (CNM). The CNM is a traffic simulation model that determines sound levels at receivers by modeling vehicles as discrete moving point sources. The vehicle energy is determined from acceleration, deceleration, idle, and cruise reference energy mean emission level curves. Sound energy attenuation is calculated from distance, ground absorption, and user input barriers. The model sums the energy at receivers from all vehicles and then calculates the Leq noise level at the receivers. It is demonstrated that the CNM predicts receiver Leq levels that are very close to STAMINA 2.0 results for constant-speed traffic. The CNM can also accurately predict sound levels at receivers located before and after intersections. In addition to the advantages of a real simulation model, the CNM is user friendly, allowing the user to place lanes and receivers using the mouse

Comparison Of Measured And Modeled Sound Levels In The Vicinity Of Traffic Noise Barriers

A detailed noise prediction model was used to compare 11 highway noise barrier locations in Florida. Insertion losses, ground effects, shadow zones, and overall trends were determined or analyzed, or both. Each location was modeled using STAMINA2.0 (current FHWA regulatory model), STAMINA2.1 (Florida\u27s version of STAMINA2.0 with state-specific emission levels), the Traffic Noise Model (often referred to as TNM; this model will replace STAMINA2.0 in the year 2002), and the University of Central Florida Community Noise Model (CNM5.0). The modeled results were then statistically compared with the measured results. Statistical evaluation results were similar for all models for overall, absolute prediction compared with the measured value, with STAMINA2.1 being slightly better. All models provided adequate results, but ranges of error were significant. When the propagation components were explored, by comparing reference levels with those behind the barrier, the TNM was significantly better. The results also provided further insight into the benefited regions behind the barrier, a more detailed understanding of how the models perform for this complex interaction with the ground and sound wave, and how background levels change the actual size and shape of the benefited region

Effect of vehicle speed on sound frequency spectra

During analysis conducted on data collected by the University of Central Florida for the Florida Department of Transportation (FDOT), which was doing research to develop reference energy mean emission levels for high-speed traffic, other interesting data trends became apparent. One such trend was the relationship of vehicle speed and sound emission spectra. The data base contained real-time one-third octave band data and vehicle characteristics (e.g., speed) and permitted a detailed review of sound emission spectra with respect to vehicle speed. The purpose of this research was to attempt to develop a mathematical relationship between increasing vehicle speed and sound emission spectra. Based on the results of this research several important conclusions were drawn: (a) a trend in the change in sound frequency spectra with respect to vehicle speed may exist for all vehicle types defined in STAMINA 2.0; (b) the change in dominant frequency followed no apparent trend with respect to vehicle speed: (c) the data base used for this research was too small for accurate mathematical modeling of the change in sound frequency versus vehicle speed; and (d) the sound attenuation provided by noise barriers may be underestimated using the current method of estimating barrier attenuation based on an effective frequency of 500 Hz regardless of vehicle speed

Now Hear This! What All Environmental Engineers Should Know About Noise Control

Environmental engineers are often called on to deal with noise-related problems. Noise affects health and quality of life for all of us. In summary, noise control should be of interest to environmental engineers for the following key reasons 1. Understanding the fundamentals is within every engineer\u27s grasp and engineers are already familiar with the operating principles of process equipment (e.g., fans, pumps, motors). This gives them an advantage in designing solutions to noise issues or avoiding problems in the first place. 2. Environmental engineers should have a good understanding of noise-related regulations as they may find themselves working in a health and safety role. 3. Understanding the difference between sound pressure level and sound power level is important for all disciplines that may be specifying equipment. Understanding why 85 dB (A) at 3 feet-although a standard specification-is not appropriate in many cases is one example. 4. Since the regulatory framework is fractured, 16 environmental engineers and planners who may eventually be involved in site selection/project development should have a clear understanding of noise when designing or approving projects. 5. It is more effective both in terms of mitigation and cost to address noise early in the design process rather than as a retrofit. If new engineers aren\u27t exposed to this, they won\u27t know how to identify problems before they arise or how to appropriately solve them after they occur. Finally, if environmental engineers aren\u27t concerned with noise control, then who should be

Florida Noise Barrier Evaluation And Computer Model Validation

The results of a project that investigated the effectiveness of in situ noise barriers in Florida are presented. The prediction accuracy of the FHWA Traffic Noise Model (TNM) is compared with STAMINA 2.0 and 2.1 (Florida-specific). A total of 20 barrier sites were visited during a 3-year period that resulted in 844 discrete 20-min equivalent sound level (L eq) measurements behind the barriers. Barrier insertion loss was determined using the ANSI indirect barrier method. A methodology was developed to estimate shadow zone length created behind highway noise barriers. All of the barriers tested were effective (\u3e5 dB:LAeq insertion loss at distances equivalent to the first row of homes, where LAeq is the A-weighted Leq) except one site because of marginal additional shielding from a berm-barrier combination. Only three sites had an insertion loss of less than 5 dB at distances representative of the second row of homes. Overall, measurements indicate that the barriers provide substantial sound level reduction for residents along the highway. TNM was the best prediction model when considering all test sites; however, the STAMINA models were more accurate at predicting source level. TNM predictions using the Average pavement input overpredicted the reference sound levels measured at these sites. TNM predictions using the OGAC (open-graded asphalt concrete) input were improved (under 2 dB:LAeq of error) over those using the Average pavement type input. This result is expected because Florida uses an open-graded asphalt friction mix