Showing papers on "Noise barrier published in 1992"
01 Jan 1992
TL;DR: In this article, a review summarizes the available information on the acoustic performance of various types of barrier and discusses the scope for cost effective application and highlights the problem of meteorological factors which may influence the results of field measurements and recommends the need for further testing under carefully monitored conditions.
Abstract: For many years barriers have been erected alongside major roads to screen residential areas from high levels of traffic noise. A very wide range of materials have been used including wood, steel, aluminium, concrete and acrylic sheeting. Some of these designs have absorptive facings on the traffic side which reduce reflected sound and are claimed to improve screening. Barriers over 8 m in height have been used for some applications and novel capped barriers, angled barriers and vegetative barriers have been tested. This review summarizes the available information on the acoustic performance of various types of barrier and discusses the scope for cost effective application. The paper highlights the problem of meteorological factors which may influence the results of field measurements and recommends the need for further testing under carefully monitored conditions. The use of computer programs to aid the design of cost effective barriers is also described. (A) This paper was presented at Eurosymposium, Delegation traffic noise in urban areas, May 1992, Nantes, France.
14 citations
Journal Article•
TL;DR: In this paper, the state of the art with respect to traffic noise abatement procedures, especially noise barriers, is described, and a report of the Transportation Research Board provides information on the design, construction and maintenance of both new and retrofit noise barriers.
Abstract: This synthesis will be of interest to highway environmental engineers, noise analysts, design engineers, maintenance personnel, planners, administrators, and others responsible for the design, selection, and maintenance of noise barriers or other traffic noise abatement policies. Information is provided on current state practice associated with noise abatement techniques and on the various products that are used. This synthesis describes the state of the art with respect to traffic noise abatement procedures, especially noise barriers. This report of the Transportation Research Board provides information on the design, construction and maintenance of both new (Type I) and retrofit (Type II) noise barriers. The design elements that are addressed include materials, the selection process, service life, foundations, drainage, aesthetics, and safety. The construction section covers technical problems related to surface effects, durability, snow damage, and costs. Other noise abatement measures such as insulation and highway design alternatives are also addressed. The issue of public demand and availability funding is included, and recommendations are made to improve the situation.
14 citations
Journal Article•
TL;DR: In this article, the effect of multiple reflections between two parallel highway noise barriers on the acoustical performance of each of the barriers has been a subject of considerable controversy and mathematical and scale modeling predict possible large reductions (degradations) in the effectiveness of noise barriers due to parallel configurations.
Abstract: The effect of multiple reflections between two parallel highway noise barriers on the acoustical performance of each of the barriers has been a subject of considerable controversy Mathematical and scale modeling predict possible large reductions (degradations) in the effectiveness of noise barriers with smooth, hard surfaces (such as masonry or concrete) due to parallel configurations However, noise measurements under conditions of actual highway traffic, typical barrier heights, and separations have yet to confirm the large degradations The methods and results of a parallel noise barrier research project performed by the California Department of Transportation are presented Field measurements of noise, traffic, and meteorology were made in three stages: before barrier construction, after construction of the near barrier, and after construction of the barrier on the opposite side of a highway The selected site was typical of many parallel barrier configurations in California More than 100 simultaneous, A-weighted, 15-min energy-averaged noise levels were measured at 11 microphones from 5 to 23 ft high and 15 to 200 ft behind the near barrier The noise data were matched by crosswind vector wind velocities and normalized for differences in traffic Analysis results showed degradations of 0 to 19 dBA, independent of wind Vector wind velocities of -3 to +11 mph caused variations in noise levels of up to 9 dBA at 200 ft behind the near barrier
8 citations
Patent•
03 Aug 1992
TL;DR: In this article, a plate-element system was proposed to satisfy ZTV LSW 88 and have narrow supports, where the plates (3, 4) were arranged with partial overlap.
Abstract: Transparent sheets of noise walls are usually clamped in in double-T supports; the supports are relatively wide and thus have an unaesthetic and disturbing effect in the environment. The new noise wall is to satisfy ZTV LSW 88 and have narrow supports. In the new plate-element system, the plates (3, 4) are arranged with partial overlap. In this region of partial overlap, cutouts (19) are provided. A fastening means (16) is connected to the support (2) through these cutouts (19) and presses the plate elements (3, 4) against the support (2).
5 citations
TL;DR: In this article, the problem related to noise barriers is simulated by a still, single-frequency, three-dimensional sound source located within two parallel screens with rigid back walls, and the solution of a reflection sound field is represented by an asymptotic solution, which is derived by the method of steepest descent.
Abstract: The problem related to noise barriers is simulated by a still, single‐frequency, three‐dimensional sound source located within two parallel screens with rigid back walls. The solution of a reflection sound field is represented by an asymptotic solution, which is derived by the method of steepest descent. We find that there is a periodic relationship between the screen‐reflection coefficient and the gap‐to‐wavelength ratio (d/λ) of the noise barrier. And there is another parameter called screen Reynolds number (Re), which regularly affects the value of the screen‐reflection coefficient. The optimum choice of noise barrier that minimizes reflection within parallel noise barriers, according to the numerical results, is Re=1, and d/λ=1/4. We also find that increasing the height of the noise barrier in order to improve its noise‐control effect is not economical.
2 citations
TL;DR: An improved design of a precast concrete noise barrier wall, comprised of posts spaced at 15 ft (4.57 m) on centers and drop-in panels, represents a cost effective, long lasting and aesthetically pleasing solution to mitigating the effects of highway noise on adjacent residential communities as mentioned in this paper.
Abstract: An improved design of a precast concrete noise barrier wall, comprised of posts spaced at 15 ft (4.57 m) on centers and drop-in panels, represents a cost effective, long lasting and aesthetically pleasing solution to mitigating the effects of highway noise on adjacent residential communities.
1 citations
01 Apr 1992
TL;DR: In this paper, the authors present the results of a measurement study performed at a highway noise barrier site located along Interstate 495 in Montgomery County, Maryland, where the objective of the study was to measure the degradation in acoustic performance due to the close proximity of a parallel barrier.
Abstract: The U.S. Department of Transportation, Research and Special Programs Administration, Volpe National Transportation Systems Center, in support of the Federal Highway Administration and seventeen sponsoring state transportation agencies, is conducting a National Pooled-Fund Study (NPFS), HP&R 0002-136, "Evaluation of Performance of Experimental Highway Noise Barriers." The first publication supporting the NPFS, FHWA-RD-90-105, "Parallel Barrier Effectiveness, Dulles Noise Barrier Project", presented measured results and evaluations of parallel barriers subject to controlled traffic conditions. This document is the second publication supporting the NPFS. It presents the results of a measurement study performed at a highway noise barrier site located along Interstate 495 in Montgomery County, Maryland. The objective of the study was to measure the degradation in acoustic performance of a highway noise barrier due to the close proximity of a parallel barrier on the opposite side of the roadway. The test site selected for measurements consisted of a contiguous arrangement of two parallel reflective noise barriers followed by a single noise barrier. Five-minute, energy-averaged, A-weighted noise levels were computed from data measured simultaneously at identical heights and offset positions behind the single and parallel barrier arrangements. Measured results show barrier insertion loss degradations of .6 to 2.8 dBA, dependent on microphone height and offset distance behind the barrier. In addition, three parallel-barrier prediction programs were used to model the study site (BARRIER, BARRIER-X, and IMAGE-3). A comparison of the measured and predicted results is presented.
1 citations
TL;DR: In this article, the authors show that the grass embankment would benefit only those living at lower levels, say below the fifth storey, and for those living on the tenth storey and above, the traffic noise is about the same regardless of whether the intervening ground is flat or sloped.
TL;DR: In this article, the authors find that there is a viscous damping factor α for the porous medium layer of the noise barrier, which affects the trapping and absorption of sound waves.
Abstract: The noise barrier problem is simulated by a still, single frequency, three dimensional sound source located within two parallel porous medium layers with rigid back walls. The solution of the reflection sound field is represented by an asymptotic solution which is derived by the method of steepest descent. We find that there is a viscous damping factor α for the porous medium layer of the noise barrier which affects the trapping and absorption of sound waves. Because there exists a layer similar to Stokes boundary layer in fluid mechanics due to the variation of thickness of the porous medium, we also find that it will be a waste if the porous medium used is too thick. The optimum choice of noise barrier which minimizes reflection within parallel noise barriers, according to the numerical results, is α = 1, while the layer thickness‐to‐wave length ratio d/λ = 1/4. We also find that increasing the height of the noise barrier in order to improve its noise control effect is not economical.