Home Wisdom teeth The main ways to combat noise. Methods of combating environmental noise pollution Global problems and noise control

Wisdom teeth

The main ways to combat noise. Methods of combating environmental noise pollution Global problems and noise control

Noise is understood as a disorderly combination of sounds of varying frequencies and intensities (strength).

In order to eliminate acoustic discomfort in cities resulting from high noise levels, the state and local governments are implementing a set of measures to reduce noise, both at its sources and along its distribution paths. The Republic of Kazakhstan has sanitary standards that strictly regulate maximum permissible noise levels in enterprises, streets of cities and towns, in residential areas, recreation areas, areas of new buildings, as well as in workplaces. Violation of established standards is dangerous to human health and is therefore unacceptable.

An important condition for protecting the population from noise exposure is strict adherence to established maximum permissible levels. One of the main ways to combat noise is to reduce it at its sources.

Currently, there are standards for the removal of residential buildings from sources of automobile noise, the construction of airports, and a sanitary protection zone is created around them depending on the class of the airport.

Taking into account the noise generated during sports competitions, it is planned to remove sports facilities from a residential building at a certain distance, based on the types of sports and the location of the housing. In this case, the presence or absence of green spaces, the number of floors of the building and the layout matter.

The fight against noise, therefore, is a fight for human health, for creating normal conditions work, life and rest. A comprehensive solution to all of the above and other issues and problems allows us to successfully combat noise in cities.

In order to select and apply more effective ways and methods to combat noise, a noise map of the city is compiled in each city, which is the main source material.

A noise map of a city (residential area, microdistrict or residential group) is compiled based on the results of measuring noise on the streets and roads of the city, based on a study of traffic conditions or the prospect of an increase in traffic intensity, the nature of traffic flows for both existing and planned cities.

To compile a noise map, the intensity of traffic on streets and roads in both directions of cars per hour, the average speed of the flow (km/hour), the number of freight transport units in the flow (as a percentage of the total number of cars in the flow), and the presence of rail transport are studied.

The noise level is measured by a sound level meter with microphones installed 7 meters from the roadway, i.e. 5 meters from the curb (international standard).

Previous materials:

2010-06-25

Modern city combines industry, transport, high density residential development, green recreation areas, sports facilities and much more. Main environmental hazards: air pollution, radiation, noise, soil pollution, electromagnetic fields and water pollution.

Noise ranks third in importance among environmental hazards in megacities. The solution to the problem of protecting people from noise should begin with the organization of constant monitoring of noise levels in the city. A tool for noise control is a noise map of the city, which shows noise levels on all main highways, in residential and recreational areas, on the territory of industrial and other enterprises, as well as around individual noisy objects. The city noise map, which is part of general environmental monitoring, is used by the authorities:

A. to develop realistically achievable noise standards for a specific city;
b. for the design and implementation of technical and other means to comply with these standards;
V. to apply sanctions to those who do not comply with these standards.

Based on the strategic noise map of the city, the master plan provides for so-called “sleeping areas” in the quiet part of the city and in the noisy part - acoustic screens, soundproofing houses, other means and measures to reduce noise (for example, removing noisy enterprises from residential areas or optimal operating modes and routes of the noisiest transport). In megacities, the most powerful source of noise is transport: ground, underground, water and air.

These are, first of all, trucks and cars, buses, trams, commuter electric trains, airplanes and helicopters, river and sea vessels. The second significant source of noise is industrial enterprises and mobile equipment, for example, construction equipment. Urban development leads to an increase in noise and its dangerous penetration into residential buildings, schools, hospitals, public and office buildings.

Urban noise is characterized by a wide spectrum and large fluctuations in space and time. To measure, calculate, standardize and control urban noise, the following three quantities are used: sound level, equivalent sound level and maximum sound level. Sound level (ultrasonic in a wide frequency range) LA [dBA] in the standardized range of octave frequency bands 31.5-8000 Hz in this moment time is determined by the formula:

where Lpi is the SPL of the ith octave frequency band, dB; kAi—correction for frequency response A for the ith octave frequency band, dB (Table 1); n = 9 - number of octave frequency bands. The equivalent sound level (EQUZ of noise that is not constant in space and time) LAeq [dBA] in the range of octave frequency bands 31.5-8000 Hz by definition is the level of constant noise, which has the same root-mean-square sound pressure as the intermittent noise under study in during a certain time interval T. It is calculated by the formula:

where T is the time of exposure to noise; LiA is an almost constant value of the sound level of non-constant noise over time τi. There is a so-called maximum sound level (MaxUS of noise that is not constant in space and time) LAmax [dBA] in the octave frequency range 31.5-8000 Hz, which by definition is the level non-constant noise corresponding to the maximum indicator of a measuring, direct-indicating device (sound level meter) during visual reading or a sound level exceeding 1% of the duration of the measuring interval during time T when recording noise by an automatic evaluation device (statistical analyzer) in dBA.

Yesterday

The first noise map of a city in our country (possibly in the world) was compiled in the early 1980s. in Leningrad by the city sanitary and epidemiological station on the initiative and under the leadership of the energetic acoustic engineer A.L. Vasilyeva. Then the equivalent sound level on the main streets of Leningrad (Nevsky Prospekt, Sadovaya Street, Bolshoi Prospekt of the Petrogradskaya Side) was, according to numerous measurements, approximately 75 dBA.

Much work on constructing noise maps was also carried out at the Research Institute of Building Physics in Moscow under the leadership of one of the leading acousticians in Russia, Doctor of Technical Sciences, Professor G.L. Osipova. In the late 1980s - early 1990s, about ten years later, this work was continued under the leadership of another famous Russian acoustician, Doctor of Technical Sciences, Professor A.S. Nikiforov, President of the Eastern European Association of Acoustics.

They and the staff of the Central Research Institute named after. acad. A.N. Krylov (acoustic engineer S.V. Popkov and others) compiled a new noise map, now not of Leningrad, but of St. Petersburg. Measurements showed that on the main streets of the city the equivalent sound level reached a value of about 85 dBA, which is ten decibels more than the noise level ten years ago. The noise in the city has subjectively more than doubled.

This is a very large increase. The sanitary standard, which is assessed by the relevant domestic and international documents, in this case according to SNiP 2303-2003 “Noise Protection” for areas directly adjacent to residential buildings, during the day is LAeq = 55 dBA (from 7:00 to 23:00) and at night - LAeq = 45 dBA (from 23:00 to 7:00).

The appearance of noise maps of cities led to the fact that local legislators were faced with the question of developing a city law on noise control, and before executive branch— on planning measures to reduce noise impact on city residents. Let us note by the way that, one might say, “the first law to combat noise” was adopted in the ancient Greek city of Sybaris*, i.e. around the 7th century BC.

There, in particular, it was strictly forbidden to make noise between sunset and before sunrise. To the barbarians surrounding Hellas, fighting noise then seemed like an unnecessary luxury. Twenty-seven centuries later, everything has changed to the opposite: those who do not fight noise are considered “barbarians.” In modern times, some of the first noise control laws were passed in England. The English Noise Abatement Act 1960 states that noise and vibration constitute a public nuisance, provided by law on health care 1936, part III.

Under the 1960 Act, local authorities could act against noise makers and take measures to reduce noise. Under this law, it was impossible to bring legal action against noise offenders that existed for a while and then ceased. New law 1969 already provided for the possibility of legal action on this matter to prevent future violations.

In English law on protection environment from Pollution, 1974, all the main provisions of the three above-mentioned laws were included, but additional provisions were also introduced. The main provisions of this law are as follows:

Violations of public order. For violators, the time for carrying out noise reduction work is determined, and specific measures are planned to prevent the harmful effects of noise. Action against violators is taken by the health department or the environmental health department, as well as the magistrate's court. In the latter case, three or more residents must file a complaint, which will trigger appropriate action.
Noise prohibition zones. According to the law, local authorities can declare any part of their area a noise-restricted area. Noise measurements are made along the perimeter of the zone and are strictly controlled.
Work planning. Here are the basic principles for planning the construction of residential buildings, roads, the functioning of industrial enterprises, airports, etc. to meet acceptable noise levels.
Construction noise. Local authorities must control construction noise and noise generated by the destruction of old buildings.

Today

The current situation is such that urban noise levels in all megacities of the world on main highways exceed sanitary standards. The public and authorities in industrialized countries have increased awareness of noise control and the need for city noise maps to help plan this control. In particular, at the request of the authorities of many Russian cities, noise maps were developed before “perestroika” by acoustics specialists from the Central Research Institute named after. acad. A.N. Krylov in Leningrad and the Research Institute of Building Physics in Moscow.

Now all this is being revived. In 2006, under the leadership of the head of the Department of Ecology and Life Safety of the Baltic State Technical University "Voenmech", President of the St. Petersburg Society for Combating Noise and Vibration N.I. Ivanov, Doctor of Technical Sciences, Professor, by order of the city authorities, work began on developing a noise map of St. Petersburg. Preliminary data - the noise level in St. Petersburg on average exceeds the permissible norm by 10-20 dBA.

This is a huge amount of excess (“Rossiyskaya Gazeta”, November 29, 2007, No. 267 (4530). The work to create a modern noise map of St. Petersburg at the European level, despite all its complexity, labor intensity, requirements for high professionalism and high cost, should be , in our opinion, has been completed and, most importantly, is widely presented on the Internet to the public: acoustics specialists, sanitary doctors and any resident of the city.

The capital's authorities are concerned about noise: almost 70% of Moscow's territory is in the noise discomfort zone (data from the State Public Institution Mosekomonitoring, which is responsible for measuring noise levels in the capital). Moscow's chief sanitary doctor, Nikolai Filatov, said that over the past 10 years, due to extra decibels in the city, the growth of cardiovascular diseases and hypertension has increased two to three times. In his opinion, loud sounds reduce the life expectancy of Muscovites by 8-12 years (“Rossiyskaya Gazeta”, 01/21/2008, No. 304 (4567).

Tomorrow

“Tomorrow” for us at the moment is in the European Union (50 years ago the USSR was in many ways ahead). The fight against noise in Western Europe is based on a solid regulatory framework. The practice here is that the European Parliament adopts the following Directives, which are aimed at complying with uniform requirements, standards, measurement procedures, etc. in the field of noise control, for example: 2000/14/EC “On noise from equipment in external environment"; 2002/49/EC “On the assessment of noise in the environment”; 2003/10/EC “On requirements for the safety and health of workers exposed to noise”; 70/157/EEC, 97/24/EC, 2001/43/EC on vehicle noise; 96/48/EC, 2002/735/EC, 2002/732/EC - railway transport; 80/51/EEC, 89/629/EEC, 92/14/EEC, 2002/30/EC - aviation transport.

All this is steadily being implemented. The legislative basis for the creation of noise maps was determined by Directive 2002/49/EC, which has the purpose of: avoiding, preventing or reducing the harmful effects of noise by ensuring public control; creation of noise reduction measures by the European Union community. The noise indicator is determined by the sound level L = Lden [dBA] per day:

where Lday is the sound level for the day, Leven is for the evening, Lnigh is for the night. The estimated day is 12 hours, the estimated evening is 4 hours and the estimated night is 8 hours. Sound levels L in this case are weighted long-term sound levels: equivalent sound levels LAeq [dBA] or maximum sound levels LAmax, dBA.

According to this Directive, noise maps must contain information on the existing or predicted acoustic situation, excess noise levels, the population and area of areas exposed to increased noise levels, as well as the number of residential buildings, hospitals and schools located in the area in question. According to European legislation, noise maps must be drawn up for all:

settlements with a population of more than 100 thousand inhabitants;
highways with traffic of more than 3 million vehicles per year;
railways with traffic of more than 30 thousand trains per year;
airports with traffic of more than 50 thousand operations per year.

Then, every five years, member states must inform the EU Commission about the main roads, main railways, main airports and agglomerations within their territories. Neighboring Member States should cooperate on strategic noise mapping and action plans for border regions.

Member States should ensure that the public is consulted on proposals for action plans, giving early and effective opportunities for participation in the preparation and review of action plans, so that the results of this participation are taken into account and that the public is informed about the decisions taken. Reasonable time frames must be provided to provide sufficient time for the public to participate in each step of the process.

Member States must ensure that strategic maps are accessible and disseminated to the public in accordance with Community legislation, in particular Council Directive 90/313/EEC on freedom of access to environmental information, incl. using available information technologies. This information must be clear, understandable and accessible. A summary of the most important points should be provided.

Minimum requirements to create a noise map:

The noise strategic map should provide data on one of the following aspects: existing, historical or future noise situations in terms of noise indicator; exceeding the limit value; the estimated number of homes, schools and hospitals in a given area that are subject to a particular noise level; estimated number of people exposed to noise.
Strategic noise maps can be presented to the public as: graphical images, numerical data in tables, data in electronic form.
On strategic noise maps of agglomerations, it is necessary to place special emphasis on noise emitted by: traffic, railway transport, airports, activities of industrial facilities, including ports.

Minimum requirements for created action plans:

At a minimum, the action plan should include the following elements: a description of the agglomeration, major roads, major railways or major airports and other sources of noise; responsible body; legal context; any limit values in place; noise display results report; assessing the expected number of people exposed to noise, identifying problems and situations that need to be improved; public consultation report; any noise abatement measures already in force and any projects in preparation; the actions that the competent authorities intend to take in the next five years, including any measures to keep the area quiet; long-term strategy; financial information: budgets, cost-benefit and benefit assessments; provisions provided for assessing the implementation and results of the action plan.
Actions that the competent authorities intend to take in such areas within their competence: road transport planning; land use planning; technical measures on noise sources; choosing less noisy sources; reduction of sound transmission; regulatory or economic measures.
For each action, the plan must contain an estimate in terms of reducing the number of people affected.

Data that must be sent to the EU special commission:

1. For agglomerations (compact spatial grouping of settlements): short description agglomerations: location, area, number of inhabitants; responsible body; noise management programs that were carried out in the past and measures; the calculation or measurement methods that were used; number of people (hundreds) living in dwellings that are exposed to each of the following bands of Lden [dBA] values 4 m above the ground surface on the most exposed facades: 55-59, 60-64, 65-69, 70-74, > 75, separately for noise from road, rail and air transport, and from industrial sources.

Numbers should be rounded to the nearest hundred (for example, values between 5150 and 5249 - to 5200; between 50 and 149 - to 100; less than 50 - to 0); estimated total number of people (hundreds) living in dwellings that are exposed to each of the following bands of Lnigh values at 4 m above ground level on the most exposed facades: 50-54, 55-59, 60-64, 65-69, > 70 , separately for road, rail and air transport and industrial sources; If presented graphically, strategy maps should have 60, 65, 70 and 75 dBA outlines and a summary of the action plan on all important aspects.

2. For major roads, major railways and major airports: general description roads, railways and airports: location, size and traffic data; characteristics of their environment: agglomerations, villages, villages or otherwise, information about land use, other main sources of noise; past noise control programs and measures; calculations or measurement methods that were used; estimated total number of people (hundreds) living outside the agglomeration in residential premises that are exposed to each of the following bands of Lden [dBA] values 4 m above the ground surface, with facades most exposed: 55-59, 60-64, 65-69, 70-74, > 75; the estimated total number of people (hundreds) living outside the agglomeration in residential premises that are exposed to each of the following bands of Lnigh [dBA] values 4 m above the ground surface, with facades most exposed: 50-54, 55-59, 60-64, 65-69, > 70; total area [km2] victimized by Lden [dBA] values higher than 55, 65 and 75, respectively - estimated total living quarters and the total number of people (hundreds) living in each of these areas must also be provided.

The disadvantage of all existing noise maps of cities and agglomerations in Russia and the European Union is the unknown accuracy and reliability of the sound levels indicated in them. The time has come to develop a method for determining the accuracy and reliability of a city noise map, and, therefore, to have a rational opportunity to increase their practical effectiveness.

To develop such a method, the authors of this article used classical method dispersion analysis of probability theory and mathematical statistics. So, we will approximate city noise by a stationary random function at normal distribution measured quantity. For such a distribution, in this case it is proposed to carry out a statistical assessment of the noise measurement results, taking into account both spatial and random fluctuations in time, as follows.

Let us present the individual results of measuring urban noise L = xij using formulas (1) and (2) in the form of a matrix of values M(xij), the horizontal rows of which contain the values xi at i different points in space with a total number of n, and the vertical columns contain the values values xj at different times j with a total number m.

If random deviations of measurements x in space do not depend on random deviations of this value in time, then the matrix of values M(xij) is transformed into a matrix of values M(xi + xj), where the value xi depends only on the measurements in space, and the value xj depends only from measurements over time. As a result, we have the following average value:

variance of deviations in space:

variance of deviations over time:

and the dispersion of deviations in space and time:

D0 = D0(xi) + D0(xj).

Let's use the following analysis of variance relation:

and, since the dependence between xi and xj in reality can at least partially exist, and usually n ≠ m, then the smallest error will correspond to the above relationship for the arithmetic mean of the cross values of the transition matrices from M(xij) to M(xi + xj) . Hence:

D(aj) = 0.5 and

D(xi) = 0.5.

Then the calculation formulas for estimating variances from above using Pearson functions Ψ(χq2) with a probability close to unity will take the form:

D~(xi) = 0.5(n/χq2) and

D~(aj) = 0.5(m/χq2).

In total, we obtain, with probability Φ(t)Ψ(χq2), where Φ(t) is the Laplace function, a statistical assessment of the “sleeve” of urban noise measurement results for sufficiently large numbers of magnitude x, practically already for nm > 100 (n ≥ 10, m ≥ 10), average value according to the formula:

And for the same nm > 100 (n ≥ 10, m ≥ 10) we obtain the following value of the largest values of x using the formula for values for a noise map of the city:

Then the greatest of possible values noise taking into account deviations only in space is calculated by the formula:

and the largest possible values, taking into account deviations only in time - according to the formula:

In the most critical cases of noise control practice, such as drawing up a noise map of the city, it is recommended to take the following reliability values:

probability Φ(t) = 0.9973 (highest degree of reliability), then t = 3.00;
probability Ψ(χq2) = 0.95, then χq2 has the values depending on n, m indicated in table. 2.

The final probability of statistical estimates of sound levels x = L [dBA], with selected Φ(t) = 0.9973 and Ψ(χq2) = 0.95 gives reliability P = Φ(t)Ψ(χq2) ≈ 0.95 indicated values for a noise map of the city according to formula (3) with accuracy [dBA]:

By setting the reliability value (for example, P = 0.95) and the accuracy value (for example, ΔL = 1 dBA), we obtain, using the proposed method, the number of measurements of equivalent sound levels Lij [dBA] in space n and in time m. The problem of representing sound levels on a noise map of a city with one number for a specific entire street, square, alley, etc. and simultaneously for the whole year can be solved by the proposed method, indicating the accuracy and reliability of this number.

Noise maps of cities and agglomerations, compiled with a given accuracy and reliability, will require an unprecedented number of measurements of sound levels in space and time and the highest speed of processing measurement results. Example: 2 km of Nevsky Prospekt in St. Petersburg with n = 10 and m = 24 will require measurements of sound levels nm = 240 per day; If these measurements are carried out 10 times a month, then the number of sound level measurements per year on Nevsky Prospekt alone will be 40 × 10 × 12 = 28,800.

However, modern acoustic equipment, computer technology, and communication means make this possible.

Conclusion

The fight against noise in the city and agglomerations in Russia must comply with the requirements of GOST R 53187-2008 “Acoustics. Noise monitoring of urban areas" and the requirements of building codes and regulations SNiP 2303-2003 "Noise Protection", as well as the requirements of relevant international standards. Legislative framework To create noise maps, we can temporarily use the following European Union Directive 2002/49/EC “On the assessment of noise in the environment”, discussed in detail above.

Currently, the main problem in the fight against noise in our country and abroad continues to be the uncertain accuracy and reliability of the sound levels indicated in noise maps. Using the method of variance analysis of probability theory and mathematical statistics, the authors proposed a method that will help solve this problem.

Electronic database of acoustic measurement equipment, computer technology of the 21st century. and global communications have reached such a level today that the use of the proposed method is a completely realistic matter. Work in this direction will be continued, in particular, by combining the efforts of the Russian Federation and the EU within the framework of national research universities, manufacturers of acoustic equipment, computer equipment and communications facilities, as well as certification centers, social institutions and power structures.

This is precisely the case when an important matter should be decisively promoted by qualified specialists together with the help of the latest measuring technology, powerful computers and the GLONASS (Global Navigation System) system. satellite system) by creating, in this case, accurate and reliable noise maps of the city.

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Dunin-Barkovsky I.V. and Smirnov N.V. Probability theory and math statistics. - M.: Gostekhizdat, 1955.
Noise control in industry. Prevention, reduction and control of industrial noise in England. Ed. J. Webb. Per. from English edited by I.I. Bogolepova. - L.: Shipbuilding, 1981.
Bogolepov I.I. Industrial sound insulation. Theory, research, design, manufacturing, control. Preface ak. USSR Academy of Sciences I.A. Glebova. Monograph. - L.: Shipbuilding, 1986.
Designer's Handbook. Noise protection in urban planning. Ed. G.L. Osipova. - M.: Stroyizdat, 1993.
Nikiforov A.S., Ivanov N.I. The problem of acoustic pollution in St. Petersburg. “The concept of development of St. Petersburg for the immediate and long-term periods with prioritization based on public consent”: Materials of the third congress of the St. Petersburg Union of Scientific and Engineering Societies. T. 1 - St. Petersburg, 1996.
Bogolepov I.I. Architectural acoustics. Textbook-reference book. Preface by ak. USSR Academy of Sciences and RAS I.A. Glebova. - St. Petersburg: Shipbuilding, 2001.
Bogolepov I.I. Construction acoustics. Preface by ak. RAS Vasilyeva Yu.S. - St. Petersburg: Publishing House of the Polytechnic University, 2006.
Ivanov N.I. Engineering acoustics. Theory and practice of noise control. A textbook for university students studying in the field of “Life Safety”. - M.: Logos, 2008.
Bogolepov I.I. Construction acoustics. Second edition. Preface by ak. RAS Vasilyeva Yu.S. Manuscript. - St. Petersburg: Publishing house Polytech. unta, 2010.

Federal Agency for Agriculture

Federal State Educational Institution
higher professional education

State University of Land Management

Department of Land Use and Cadastres

Noise in the city and means of protection

Completed: art. gr. 22 to 2

Reshetnikova A.A.

Checked: Art. teacher

Introduction

Noise pollution in cities is almost always local in nature and is mainly caused by means of transport - urban, railway and aviation. Already on the main highways major cities noise levels exceed 90 dB and tend to increase by 0.5 dB annually, which is the greatest danger to the environment in areas of busy highways. As medical research shows, elevated levels noise contributes to the development of neuropsychiatric diseases and hypertension. The fight against noise in the central areas of cities is complicated by the density of existing buildings, which makes it impossible to build noise barriers, expand highways and plant trees that reduce noise levels on the roads. Thus, the most promising solutions to this problem are the reduction of the own noise of vehicles (especially trams) and the use of new noise-absorbing materials in buildings facing the busiest highways, vertical gardening of houses and triple glazing of windows (with the simultaneous use of forced ventilation).

A particular problem is the increase in vibration levels in urban areas, the main source of which is transport. This problem has been little studied, but there is no doubt that its importance will increase. Vibration contributes to faster wear and destruction of buildings and structures, but the most significant thing is that it can negatively affect the most precise technological processes. It is especially important to emphasize that vibration brings the greatest harm to advanced industries and, accordingly, its growth can have a limiting effect on the possibilities of scientific and technological progress in cities.

State of the problem of reducing transport noise

An important problem in Moscow, like any other large city with a lot of transport and industry, is the high noise level, which, according to environmental scientists, causes a lot of trouble for European residents.

Over 75% of the capital's territory is under the influence of acoustic load 5-10 dB above normal (55 dB during the day and 45 dB at night). At the same time, according to various sources, 3-6 million Muscovites live in areas of increased noise pollution, who are forced to constantly be exposed to noise equal to 90-100 dB during the day and 70 dB at night. According to experts, the most unfavorable situation has developed in South Butovo, and the calmest in the North-Western District.

The main culprit of noise, of course, is transport, which accounts for 70-90% of all noise pollution. Thus, due to the proximity of Vnukovo airport, the areas that suffer the most are Solntsevo, Teply Stan, Yasenevo and Troparevo. In turn, Sheremetyevo influences Mitino, Molzhaninovsky district - on Zelenograd, and Ostafyevo - on the same South Butovo.

In second place in terms of noise generated are industrial facilities, affecting 10-15% of its territory in the capital. In addition, there are many other sources of noise pollution: for example, elevators, heating units, boiler rooms, pumping stations and electrical substations. Therefore, it is not surprising that in the last 10 years, the majority of young residents of the capital have noticeably weakened hearing by the time they reach adulthood: they hear 5-20% worse than normal, as if they were not 18, but 85 years old.

IN general case methods for reducing transport noise can be classified in the following three areas: reducing noise at the source of its occurrence, including removing vehicles from service and changing their routes; reduction of noise along the path of its propagation; the use of sound protection means when perceiving sound.

The use of a particular method or combination of methods depends largely on the extent and nature of the noise reduction required, taking into account both economic and operational constraints.

Any attempt to regulate noise must begin with identifying the sources of that noise. Despite the presence of significant similarities between various sources, they are quite dissimilar from each other for the three modes of transport,
- road, rail and air.

Of the three main modes of transport, road transport has the most adverse acoustic impact. Cars are the predominant source of intense and long-lasting noise, with which no other can be compared. The noise created by moving cars is part of the traffic noise. In general, the greatest noise is generated by heavy vehicles. At low road speeds and high engine speeds, the main source of noise is usually the power plant, while at high speeds, lower speeds and lower engine power, noise caused by the interaction of tires with the road surface can become dominant. If there are uneven surfaces on the road, the noise of the leaf spring suspension system, as well as the rumble of the load and body, may become predominant.

It should be noted the great importance of measures to limit the spread of noise that has already arisen, along with the main method of reducing road transport noise by suppressing the source of its origin. These measures include improving the design of roads and their alignment, regulating traffic flows, using screens and barriers, and revising the general concepts of land use near major transport routes.
Additional measure, which applies to all modes of transport, is to improve the design and soundproofing characteristics of buildings to reduce noise within them.

Rail transport, in contrast to road and air transport, is not developing at such a rapid pace. However, there are signs that railways will begin to play a new role. Following the introduction of high-speed trains in Japan and France, many countries decided to increase train speeds and passenger volumes, thereby increasing the competitiveness of railways. The expansion of the railway network and the increase in train speeds will cause an increase in noise, and related problems of protecting the environment from it will arise. Similar situations have already arisen in Japan, where the public protested against high-speed trains. As a consequence of these protests, the Japanese State Railways Administration decided to postpone the construction of new lines leading to Tokyo Narita Airport.

The irritation caused by air traffic noise is mainly due to the introduction of jet aircraft into commercial airline service in the late 1950s. Since then, the number of commercial and private jet aircraft in daily operation has exceeded 7 thousand. During this period, significant attention was paid to aircraft noise reduction. The solution to the problem under consideration was carried out in the following three main directions. The first and probably most important direction comes down to the study of the main sources of noise and the development, in particular, of less noisy power plants. The second direction is related to the streamlining and introduction of control of aircraft flights in the vicinity of airports. Finally, the third direction - measures not directly related to changes in the operating conditions of aircraft - rational use land plots both on the territory of the airport itself and in its surroundings with increased sound insulation of buildings and structures exposed to high-level noise.

Means and methods of noise protection

General classification of means and methods of noise protection.

Applies to means and methods of noise protection used in workplaces of production and auxiliary premises, on the territory of industrial enterprises, in residential and public buildings, as well as in residential areas of cities and towns.

1 Means and methods of noise protection in relation to the protected object are divided into:

· means and methods of collective defense;

· individual protection means.

2 Collective protection means in relation to the noise source are divided into:

means that reduce noise at its source;

· means that reduce noise along the path of its propagation from the source to the protected object.

2.1 Means that reduce noise at the source of its occurrence, depending on the nature of the impact, are divided into:

means that reduce noise excitation;

· means that reduce the sound-emitting ability of a noise source.

2.2 Means that reduce noise at the source of its occurrence, depending on the nature of noise generation, are divided into:

· means that reduce noise of vibration (mechanical) origin;

· means that reduce noise of aerodynamic origin;

· means that reduce noise of electromagnetic origin;

· means that reduce noise of hydrodynamic origin.

2.3 Means that reduce noise along the path of its propagation, depending on the environment, are divided into:

· means that reduce the transmission of airborne noise;

· means that reduce the transmission of structural noise.

3 Noise protection means, depending on the use of an additional energy source, are divided into:

· passive, in which no additional energy source is used;

· active, in which an additional source of energy is used.

4 Means and methods of collective noise protection, depending on the method of implementation, are divided into:

· acoustic;

· architectural and planning;

· organizational and technical.

4.1 Acoustic noise protection devices, depending on the principle of operation, are divided into:

· sound insulation means;

· sound absorption means;

vibration isolation means;

damping means;

· noise suppressors.

4.2 Sound insulation means, depending on the design, are divided into:

· soundproofing fencing of buildings and premises;

· soundproofing casings;

· soundproof cabins;

· acoustic screens.

4.3 Sound absorption means, depending on the design, are divided into:

· sound-absorbing linings;

· volumetric (piece) sound absorbers.

4.4 Vibration isolation means, depending on the design, are divided into:

· vibration-isolating supports;

· elastic gaskets;

· structural breaks.

4.5 Damping means, depending on the damping characteristics, are divided into:

· linear;

· nonlinear.

4.6 Damping means, depending on the type of damping, are divided into:

· elements with dry friction;

elements with viscous friction;

· elements with internal friction.

4.7 Depending on the principle of operation, noise silencers are divided into:

· absorption;

reactive (reflex);

· combined.

4.8 Architectural and planning methods of noise protection include:

· rational acoustic solutions for building layouts and master plans of facilities;

· rational placement of technological equipment, machines and mechanisms;

· rational placement of workplaces;

· rational acoustic planning of zones and modes of movement of vehicles and traffic flows;

· creation of noise-protected zones in various places where people are located.

4.9 Organizational and technical methods of noise protection include:

· use of low noise technological processes(changes in production technology, method of processing and transporting material, etc.);

· equipping noisy machines with remote control and automatic control;

· use of low-noise machines, changes in the structural elements of machines, their assembly units;

· improvement of technology for repair and maintenance of machines;

· use of rational work and rest schedules for workers in noisy enterprises.

5 Personal protective equipment against noise, depending on the design, is divided into:

· anti-noise headphones covering auricle outside;

· anti-noise liners covering the outer ear canal or adjacent to it;

· anti-noise helmets and hard hats;

· anti-noise suits.

5.1 Anti-noise headphones are divided into:

· independent, having a hard and soft headband;

· built into a headgear or other protective device.

5.2 Anti-noise earplugs, depending on the nature of use, are divided into:

· reusable;

· single use.

5.3 Anti-noise liners, depending on the material used, are divided into:

· hard;

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Ministry of Education and Science of Ukraine

Odessa National Maritime University

on the topic: Noise problems in cities

Performed:

Kiyutina A.A.

Odessa -2014

Introduction

3.2 Sound insulation of buildings

4.2 Freight car noise

Conclusion

List of used literature

Introduction

Noise pollution in cities is almost always local in nature and is mainly caused by means of transport: urban, railway and aviation. Already now, on the main highways of large cities, noise levels exceed 90 dB and tend to increase by 0.5 dB annually, which is the greatest danger to the environment in areas of busy transport routes. As medical studies show, increased noise levels contribute to the development of neuropsychiatric diseases and hypertension. The fight against noise in the central areas of cities is complicated by the density of existing buildings, which makes it impossible to build noise barriers, expand highways and plant trees that reduce noise levels on the roads. Thus, the most promising solutions to this problem are the reduction of the own noise of vehicles (especially trams) and the use of new noise-absorbing materials in buildings facing the busiest highways, vertical gardening of houses and triple glazing of windows (with the simultaneous use of forced ventilation).

1. Trends in the acoustic impact of transport

As far back as ancient Rome, there were legal provisions regulating the noise levels generated by vehicles of that time. But only recently, from the beginning of the 70s of the XX century. When developing prospects for the development of transport, their impact on the environment began to be taken into account. The environmental movement has become so powerful that many promising developments in the field of transport have been considered environmentally undesirable. This environmental revolution occurred not as a result of the public’s reaction to environmental pollution in all its manifestations, but as a result of a combination of increased public concern and the need to maintain environmental cleanliness at least at the level that had developed by that time due to the intensive development of transport systems and means, and urbanization. For example, road transport in the countries of the Organization for Economic Co-operation and Development (OECD) for 1960-1980. increased 3 times, air - 2 times. The urban population of these countries increased by 50%, and the number of cities with more than 1 million inhabitants. doubled. During the same period, many highways, airports and other large transport facilities were built.

With such development of transport, it is not surprising that noise pollution of the environment has constantly increased.

But it should be pointed out that since the late 70s, mainly due to experimental studies related to the limitation of noise generated by individual vehicles and aircraft, and also partly as a result of the improvement of roads and sound insulation of buildings, the previously achieved level of transport noise has tended to stabilize .

Taking into account the trends in noise reduction over the next few years, we can come to the conclusion that the corresponding indicators are expected to improve. In OECD countries, more stringent noise control requirements are imposed on freight transport vehicles. The new rules should lead to significant changes that will particularly affect those parts of the population exposed to noise generated by heavy goods vehicles. In addition, some countries are introducing better road design standards, as well as legislation to ensure that people whose homes are exposed to significant traffic noise have the right to request additional soundproofing measures for their homes.

By introducing more stringent measures to reduce vehicle noise at its source, further real reductions in human exposure to noise can be expected. Back in 1971, in the UK, when developing a design for low-noise heavy vehicles, it was recommended to proceed from a standard noise level of 80 dBA. Even if this project has demonstrated that current technology can achieve a certain degree of noise reduction required while being economically acceptable, there still remain technical and political difficulties in establishing legislative measures that would facilitate the implementation of the above design standards in production. It is estimated that if these technical policies could be implemented, the number of people exposed to noise levels of 65 dBA or more would be significantly reduced.

With regard to noise generated by civil aircraft, most studies suggest that implementing measures to reduce its impact will take quite some time. long time. This is mainly due to two reasons. Firstly, the new generation of aircraft will be less noisy, and secondly, all old-type aircraft that do not meet modern noise regulations will be taken out of service by the end of the next decade. The pace of renewal of the existing aircraft fleet will, of course, depend on many factors, mainly on the pace of replacement of aircraft with new generation models, as well as on a possible shift in timing due to the expected increase in the fleet of general purpose aircraft and the use of helicopters. Taking into account these factors, the forecast for OECD countries indicates that in the United States there will be a decrease in the number of people exposed to noise levels of 65 dBA by approximately 50-70%; in Denmark by - 35%, and in France, according to the results of the calculation for the five most important airports, there will be a reduction in the area exposed to aircraft noise by - 75%. Although the number of people who will benefit from these interventions is small compared to the substantially larger number of people exposed to unacceptably high levels of ground traffic noise, these interventions represent a significant step forward.

Quantitative indicators of exposure to noise from rail transport remain largely unchanged in most countries. It is expected that the state of affairs in this area will remain unchanged for the foreseeable future. However, there are areas where railway noise is a major source of irritation. Introduction to Lately the introduction of high-speed trains and high-speed urban lines leads to an expansion of areas exposed to new noise sources. Therefore, people's living conditions can be improved if serious measures are taken to reduce noise.

2. State of the problem of reducing transport noise

In general, methods for reducing transport noise can be classified into the following three areas: reducing noise at its source, including removing vehicles from service and changing their routes; reduction of noise along the path of its propagation; use of sound protection equipment when perceiving sound.

The use of a particular method or combination of methods depends largely on the extent and nature of the noise reduction required, taking into account both economic and operational constraints.

Any attempt to regulate noise must begin with identifying the sources of that noise. Despite the presence of significant similarities between various sources, they are quite dissimilar from each other for three modes of transport - road, rail and air.

It is often quite difficult to determine the relative contribution of different noise sources in complex vehicles. Therefore, if the task arises to reduce the noise of a given vehicle, valuable information can be obtained based on an understanding of the mechanism for generating noise from these sources when the operating conditions of the vehicle change. Due to the fact that the overall noise of a vehicle is determined by a number of sources, it is necessary to try to obtain data on the radiation characteristics of each of these sources separately and determine the most effective methods for reducing the noise of a particular source, as well as which method for reducing the overall noise of a vehicle means will be the most economical in this case. It should be noted the great importance of measures to limit the spread of noise that has already arisen, along with the main method of reducing road transport noise by suppressing the source of its origin. These measures include improving the design of roads and their alignment, regulating traffic flows, using screens and barriers, and revising the general concepts of land use near major transport routes. An additional measure that applies to all modes of transport is to improve the design and soundproofing of buildings to reduce noise within them.

The irritation caused by air traffic noise is mainly due to the introduction of jet aircraft into commercial airline service in the late 1950s. Since then, the number of commercial and private jet aircraft in daily operation has exceeded 7 thousand. During this period, significant attention was paid to aircraft noise reduction. The solution to the problem under consideration was carried out in the following three main directions. The first and probably most important direction comes down to the study of the main sources of noise and the development, in particular, of less noisy power plants. The second direction is related to the streamlining and introduction of control of aircraft flights in the vicinity of airports. Finally, the third direction is measures not directly related to changes in the operating conditions of aircraft - rational use of land both on the territory of the airport itself and in its surroundings with increased sound insulation of buildings and structures exposed to high-level noise.

3. Limiting exposure to road transport noise

3.1 Reducing traffic, improving road design and regulating land use

Traffic intensity.

The most obvious way to reduce vehicle noise is to reduce traffic volume by shifting traffic flow. Dividing the traffic flow, for example, in half, generally leads to a reduction in traffic noise levels by 3 dBA. However, closing sections of the road to all types of road transport may create certain difficulties. For example, when a general ban on motor vehicle traffic was imposed from 10 p.m. to 6 a.m. in Nuremberg, about 600 preferential documents were issued for the right of normal access for residents, and the traffic caused by these permits significantly weakened the effectiveness of this general ban.

The effect of traffic restrictions depends not only on the displaced traffic flow, but also on the volume of traffic both before and after the restrictions are introduced. Reducing traffic intensity by half leads to a reduction in the equivalent noise level, provided other parameters remain unchanged. But traffic intensity and vehicle speed, generally speaking, are strongly correlated quantities. A decrease in traffic volume is usually associated with an increase in traffic speed, so the expected optimal benefit from reducing traffic volume is not achieved. In addition, the movement of traffic flow leads to an increase in noise on other roads of the transport system. Nevertheless, the fact that the level of transport noise and traffic intensity are related by a logarithmic relationship can be used in the right direction. For example, you can remove traffic flow from a lightly used road and transfer it to an already heavily used one. This will result in a slight increase in noise on a heavily used road, especially if it has been pre-designed for heavy traffic. At the same time, significant results will be achieved in reducing noise on lightly loaded roads. Consequently, it is possible to achieve very significant noise reduction for a significant number of people by creating bypass routes specifically designed for high traffic volumes and easing the tension of the transport network that penetrates residential areas.

In large and small cities where bypass routes have not yet been created, you can switch traffic flow at night to the streets where commercial enterprises are located.

Limiting the number of heavy trucks in the traffic flow is also aimed at reducing road transport noise. These measures usually take the form of bans on the entry of trucks into a certain area or on the entry of all vehicles above a certain carrying capacity into the city, as well as restrictions on entry at certain times, usually at night, Saturdays and Sundays.

Theoretically, reducing the speed of road transport is one of the most effective measures to limit the noise level of road transport. On high-speed roads, reducing the average vehicle speed by 2 times can lead to a reduction in the equivalent noise level by 5-6 dBA. But in practice it is difficult to achieve a reduction in vehicle speed. Despite the introduced speed limits, most vehicles exceed this limit.

Success in reducing speed can be achieved by installing raised areas on the road surface or transverse stripes on the road, which allow drivers to feel the speed of the vehicle. Other methods include narrowing the road and bending the road alignment.

Road design.

The noise emitted by motor vehicles depends on both the vertical and horizontal outline of the road, as well as the type of road surface.

Issues of construction and design of roadside barriers are considered when designing a road. Typically, an acoustic barrier takes the form of a vertical wall, although other forms have also been widely used, and attempts have been made to improve the aesthetic rather than shielding characteristics of barriers. When designing an effective sound barrier, the following goals are set: the barrier must have sufficient mass to attenuate sound and be accessible for routine maintenance and repair; installing a barrier should not lead to an increase in accidents.

In addition, the construction of the barrier must be economical.

To provide optimal sound protection, the barrier should be located near the noise source or near the object being protected from noise. The barrier should, if possible, completely hide the fenced section of the road, excluding the visibility of this section from the windows of the protected buildings or various points of the protected space. Although the mass of the barrier should not be significant, it is important to ensure that all gaps in the barrier structure are thoroughly sealed. A hole or gap in the barrier structure can lead to a significant reduction in its shielding capability, and the presence of these defects can cause resonance effects, which can lead, in turn, to a change in the nature of the sound converted by the barrier, in which broadband noise changes into noise containing discrete tones.

The sound energy generated by the traffic flow can be reflected using efficient sound receivers on the side of the barrier wall facing the source. If there are sound barriers on both sides of the road, there may be further complications, caused by multiple reflections occurring between the walls of the barrier. In certain configurations, the shielding potential of each barrier can be significantly reduced as a result of exposure to additional noise refracted through the barrier from imaginary sound sources.

Mention should also be made of barriers made in the form of an embankment, as well as barriers such as “caves” in rocky soil. Typical absorbent barriers consist of hollow box panels that have a perforated or exposed metal plate on the road side. The box is then filled with sound-absorbing material such as mineral wool.

Cut roads are usually well shielded by the edge of the shield wall, although reflections from a distant wall may reduce the shielding performance.

On roads located on an embankment or overpass, noise problems are more severe, although some shielding does occur at sound pickup points located below the edge of the embankment or parapet.

Calculation of road intersections.

In order to reduce noise levels, it is important to consider at the road intersection design stage the organization of traffic flow in order to minimize the number of accelerations and decelerations of vehicles. The same goal is set when developing road transport management plans. These plans are designed to reduce travel times and reduce the number of accidents.

A traffic light system has been developed and installed in almost every major city in the world. Unfortunately, the impact of these measures on noise generated by road transport is not as significant as expected. This is partly due to the fact that the improvement in the organization of traffic flow through the introduction of these control systems gradually leads to the fact that the load on the system increases, its rapid overflow and (or) an increase in the intensity of traffic flow occurs.

Another measure to limit the flow of cars passing through road intersections is to turn off traffic lights at intersections of roads with low traffic volumes at night. However, this does not lead to any systematic reduction in noise levels and is due to the fact that vehicle speeds are overestimated, which negates the benefits associated with eliminating the process of starting vehicles in the presence of traffic lights.

Road surface design.

Research has shown that some improvements in noise reduction can be achieved through appropriate tread design and tire design. However, designing tires with significantly reduced noise levels conflicts with the urgent need to ensure traffic safety, prevent heating of the tread and ensure vehicle efficiency. Consequently, the creation of promising alternative road surface designs opens up great opportunities for noise reduction.

Important, from the point of view of limiting noise, is, apparently, the structure of the road surface itself; whether it is formed by a bituminized material with a random structure pattern, or a concrete coating with a dominant transverse structure.

In the UK, measurements were carried out that made it possible to establish a basic relationship between the skid resistance of a car on a given road surface and the total noise level generated by cars traveling at high speeds on a given road surface. It was found that this ratio is statistically independent of the structure of the road surface material. Unfortunately, while this result is useful in establishing standards for pavement design that take safety and environmental considerations into account, it exposes the tension that exists between defining pavements that have low level noise and satisfactory safety standards at high speeds. For example, a smooth road surface may be relatively quiet, but at the same time completely unsafe for driving in wet weather.

Some road surfaces combine low noise and satisfactory lateral skid resistance characteristics. Such road surfaces usually have a porous structure that is moisture permeable, but at the same time has satisfactory sound absorption in the frequency range from 400 Hz to 2 kHz.

An experimental pavement on corrugated concrete sections of the ring road east of Brussels resulted in a reduction in noise levels of approximately 4 dBA for vehicles traveling at 70 km/h and by 5.5 dBA for vehicles traveling at 120 km/h. h. It was found that noise reduction can be achieved with other types of porous road surfaces. In Sweden, for example, such data were obtained for a porous road surface composed of a stone core selected according to its granulometric composition with emulsion asphalt as a binder, and in Canada for a road surface composed of an “open” type mixture with a thin protective layer of bitumen. In the latter case, it was found that the noise reduction was 4-5 dBA compared to the noise level on roads with conventional asphalt pavement and 3 dBA compared to worn concrete pavement, which has much less resistance to lateral drift than a road surface composed of “open” type mixtures and covered with a thin protective layer of bitumen.

However, in Norway and Sweden, problems have arisen regarding the durability of these road surfaces due to the use of studded tires during the winter months. These tires crush the surface layer into a fine powder, which then clogs the pores of open-type road surfaces, gradually reducing their sound absorption

Land use planning.

The noise level near the highway is quite significant. When identifying a new road route in an existing urban area, most existing structures must be preserved, so road layout and design are critical factors in minimizing vehicle noise. If the road passes through an area that has not yet been developed or is planned for redevelopment, consideration may also be given to limiting the impact of noise by appropriately regulating the land use of the areas surrounding the road.

The possibilities for successful road planning are determined by the size of the available space, as well as the nature of the terrain and the zoning policies applied. When planning a road, it is necessary to ensure as much as possible longer distance between the noise source and the area most sensitive to noise; rational placement of places of human activity that are compatible with some noise exposure, such as parking lots, open spaces, buildings and facilities for utility purposes; the use of architectural forms and green spaces as barriers to shield areas sensitive to noise.

Residential areas can be protected from traffic noise by placing them at a sufficient distance from the noise source. However, designers consider this approach not economically justified. This is often true, since, for example, in buildings located adjacent to a highway (less than 100 m), the noise level rarely drops below 70 dBA. However, under certain circumstances, spatial separation of buildings and roads should be considered as the only positive solution to the problem. This is especially true in conditions of heterogeneous redevelopment or development of the area, when blocks of high-rise buildings are being built, which cannot be easily screened with barriers and must be located as far from the road as local conditions allow.

Low-rise residential buildings can, in most cases, be protected from noise by some form of screening or green space.

3.2 Sound insulation of buildings

Building design

The need for expensive building envelopes with high sound insulation properties can be minimized if the shape and orientation of the building is planned to take into account the impact of noise from the road.

The purpose of this approach is to avoid reflected sounds from any wall surface facing noise-sensitive areas of the building itself or from a building located nearby. The shape of a building can be used to provide its own acoustic protection. Some parts of such a building (walls with ledges and balconies) provide acoustic protection from noise from the road.

Inside any building there are rooms in which people will be less exposed to outside noise, since noise from the road is usually the only irritating factor For rooms directly facing the road, noise-sensitive rooms must be identified and located on the other side of the building.

Soundproofing of building elements.

The physical characteristics of walls that contribute to good sound insulation are low rigidity, high damping levels and high mass. Thus, a thick stone wall will have higher sound insulation than a thin glass panel.

Noise generated by road traffic often has high levels in the low frequency range, where the sound insulation of the building envelope is usually determined by the mass of the building envelope.

A two-layer structure will have greater sound insulation than a single-layer structure of the same total mass. For example, a wall made of hollow bricks will have higher sound insulation than a wall made of solid bricks. The sound insulation of a two-layer building envelope depends on the physical characteristics of each layer and the nature of the connections between them. The farther apart the layers are located and the less connection between them, the better the sound insulation of this two-layer fence will be. The propagation of sound through the framing structure can be reduced if so-called lip seals are used for at least one of the layers. The sound insulation of two-layer building envelopes can be improved by filling the gap between the layers with sound-absorbing material such as fiberglass.

The wall should not contain any easily opening elements, such as doors and windows, since their weak sound insulation will reduce the sound insulation properties of the enclosing structures. But buildings are rarely designed with this consideration in mind, since windows provide natural light, ventilation as well as visual contact with the outside environment.

Double-layer building envelopes in the form of double glazing can significantly improve sound insulation. The most important factor determining the effectiveness of double glazing is the gap between the composite glass panels. Increasing the gap to 200 mm results in overall greater sound insulation.

If the glass sheets are not installed parallel, you can get a slight improvement in sound insulation both in the area where the wavelengths coincide and in the area where the effect of cavity resonance is observed. However, the overall noise reduction achieved by tilting one sheet of glass rarely justifies the additional cost of building a building envelope. transport noise city

A similar improvement in sound insulation can be achieved by gluing strips to the outline of the opening window. However, opening the window cleanly can lead to disruption of the ability of such strips to completely cover the gaps along the contour. When opening a window to ventilate the room, the sound insulation drops sharply.

When windows are tightly closed or sealed, natural ventilation cannot be used. You need either a mechanical ventilation system or an air conditioning system. Such systems must be carefully selected to provide adequate ventilation without exceeding acceptable noise levels. The ventilation outlets and inlets of these systems should not face the road. They must be equipped with reflective baffles or shields in order to block noise transmission paths.

The roof of a building is usually the only significant transmission path for traffic noise when the building is located below highway level or the roof has a gradual slope that exposes a large area of the roof to direct noise. There are usually many air gaps in the roof of any structure, which alter the sound insulation. This could be achieved even with a heavy tile covering. Any openings in the roof (chimneys or exhaust pipes) will contribute to the spread of noise. If these holes are not very large, they should be sealed. But in most cases, ventilation in the roof cavity has important, therefore, these openings must be located on the side of the building that is not facing the road, or these openings should be equipped with a grille or soundproof canopy.

4. The problem of reducing noise from railway transport

4.1 Reducing noise during the interaction of wheel and rail

Two opposing methods can be proposed to reduce the noise emitted by the interaction of the complex and the rail.

The first of these methods comes down to reducing the unevenness of wheels and rails as much as possible. In this case, the greatest effect is achieved by eliminating irregularities in the one of the specified elements whose unevenness is greater. With this approach, the variable component of the interaction force between the wheel and the rail decreases. This method gives the best results in practice. This presupposes the ongoing maintenance of the rail surface in a state free from wave-like wear and the use of disc brakes to reduce the formation of irregularities on the wheel tires. It is also possible to use some types of shoe brakes in which the cast iron pads are replaced with brake pads made of composite materials, although these pads will still act on the wheel tire. This replacement of pads helps reduce rolling noise, since wavy irregularities will not form on the surface of the wheel.

With the second method, you can try to reduce the response of noise-emitting elements. The most obvious way is to increase the damping of the wheels or rails. This attempt was made while searching for measures to reduce the grinding of wheels when passing curved sections of the track. However, this attempt did not lead to any significant reduction in noise when wheels rolled along a straight or curved section of a large radius track. The reason for the failure of this attempt is not clear, but it can be assumed that the friction that occurs at the contact indentation site already exceeds the value of the additional damping introduced.

Another method of reducing radiated noise was also tried by installing an acoustic screen on the body in the form of aprons covering the bogies. The effect of this method was also insignificant: the largest noise reduction was 2 dBA. The difficulty of aprons is that they usually cannot be made low enough to completely shield wheel noise due to strict restrictions on the established size of rolling stock to prevent collisions with various track devices. In addition, if we accept the correctness of the theory that the rail is the main source of noise radiation, then shielding the wheels is unlikely to lead to a significant reduction in noise.

Another possible solution is to install extended acoustic screens along the track. However, doubts arise regarding the effectiveness of acoustic screens installed close to the track. Typically, acoustic screens are only effective when approximately their height exceeds the wavelength of sound traveling in the direction of the screen. Consequently, it can be assumed that the screens will be effective only in the region of the upper frequencies of the wheel-rail interaction noise spectrum, and even then only in the case when each railway track is fenced with acoustic screens on both sides.

4.2 Freight car noise

For operational reasons, the spring suspension system of a freight car should be as economical as possible. The consequences of this are obvious. Freight cars are built relatively crudely, without proper measures to limit their rattling and rumble. The damping of the spring suspension system is usually insufficient, and vibrations can be easily transmitted to the car body. Moreover, the cars are noisier when running empty than when operating loaded: the load leads to both mass stabilization and some damping.

May be offered technical means reducing the noise of freight rolling stock to the noise level of passenger cars, but their implementation will encounter a number of obstacles. Research shows that it is possible to reduce the noise level of freight cars using disc brakes by 5 dBA. However, in addition to the considerations associated with modifying the brake system, there are usually other compelling arguments in favor of retaining cast iron shoe brakes. The changes in braking force with driving speed are significantly different for the two brake systems under consideration. Therefore, the use of freight cars with different brakes in the same train cannot be allowed. Consequently, the operation of international freight trains with their usual rearrangement and variety of cars requires that all cars, new or old, of any accessory, have the same braking system.

Reducing the noise level of rattling and rumble, as well as eliminating resonant vibration modes of rolling stock bodies, does not present any particular technical difficulties, but the implementation of appropriate measures requires costs. Similarly, the use of more advanced spring suspension systems or freight cars equipped with bogies, rather than the use of extended cars with two-axle wheelbases, leads to grinding noise in curved sections of the track. Converting old freight cars to a new, modern chassis is associated with high costs.

5. Reducing exposure to noise from air transport

5.1 Reducing exposure to noise generated by aircraft

Introduction of restrictions on aircraft operation

Airspace controls developed in a number of countries reduce the impact of noise generated by aircraft by limiting their operation to certain times of day. The practical implementation of these measures comes down to limiting the time during which aircraft flights are allowed at the airport. At Geneva International Airport (Switzerland), with the approval of the Federal Civil Aviation Administration, a restriction on takeoffs and landings at night between (from 22.00 to 6.00) has been introduced for all types of air traffic.

There are also examples of partial restrictions on takeoffs and landings at night, and in this case we are talking about airports where the administration allows certain types of operations at night based on the type or class of aircraft. For example, at Palm Beach International Airport in Florida, scheduled takeoffs of noisy aircraft are prohibited between 10 p.m. and 7 a.m.

Some airports have imposed restrictions on the total number of operations carried out in a given period of time. For example, London Heathrow International Airport allows 3,650 aircraft movements at night throughout the summer, while Gatwick Airport allows 4,300 aircraft operations during the same period.

Restricting aircraft operations to certain hours of the day is considered the most stringent type of noise control in the industry. These restrictions can have significant economic impacts on air transport, especially when air travel spans multiple time zones. Nevertheless, airports in many countries have introduced some types of partial or complete restrictions on the operation of aircraft during certain hours.

Perimeter rule.

This rule is used to limit the range of flights carried out when departing from a given airport. Flight range can affect noise levels in a variety of ways.

First, it can determine the capacity of a particular airport. In general, fewer operations result in less overall noise exposure. With limited flight ranges, the maximum take-off weight of the aircraft is less, since it is determined mainly by the reserves of required fuel. A lower take-off weight allows for greater lift to be realized, which in turn leads to a reduction in the size of the noise contour created by the aircraft on the earth's surface. Finally, the type of aircraft required for shorter range flights may not be as noisy as those required for longer range flights.

This procedure requires some attention, especially in cases where there are nearby airports that operate without such restrictions. At John Wayne Airport in California, flight range restrictions have been introduced: flights with a range of no more than 500 miles are allowed there. But there are other airports in the Los Angeles region that could handle aircraft without these restrictions. Thus, the application of such a procedure is very limited, and its legal aspects may be questionable.

Flight routes with minimal noise levels.

We will consider special flight routes for takeoff and/or landing conditions that avoid overflying noise-sensitive areas. The flight route in this case is a projection onto the plane of the earth's surface of the spatial flight path of the aircraft. This term is used for both takeoff and approach. In order to reduce irritant effect noise, it is necessary to link the selected flight routes with the location of the aircraft in space relative to the earth's surface or territory used for residential construction.

Many airports have prescribed flight paths for aircraft that are located in areas of uninhabited land, including water areas, agricultural land, forests, steppes, or open spaces.

This makes it possible to significantly reduce the impact of noise on populated areas of the capital.

Standards governing noise emissions.

In general, the noise generated by each aircraft operation must comply at one or more points with specified limits. Typically, in practice, the maximum noise level measured outside the airport boundary and applicable to any type of aircraft in operation is used.

Penalties for violations of established noise limits can vary widely.

Often, airlines that commit such violations are given warnings without any legal sanctions. More common, however, is the imposition of a fine, since the violation is often an act punishable by court.

Noise control.

The fundamental possibility of round-the-clock monitoring of compliance with established noise limits at airports on the basis of constantly operating measuring equipment has long been proven, and the interest of airport administrations in the installation and use of such equipment and devices is increasing over time.

5.2 Noise mitigation (ground measures)

Flight intensity restrictions

Such restrictions set a limit on the number of aircraft operations at an airport that can be carried out within a certain period. These restrictions include regulation of the number of takeoffs and landings of transport aircraft allowed at a given airport during the day. For example, at Washington National Airport, only 37 transport aircraft operations are allowed between 7:00 a.m. and 9:59 p.m.

There is a trend to provide incentives to those airlines that make extensive use of noise abatement measures and low-noise aircraft types to generally reduce the adverse impacts of aircraft noise. However, it should be noted that limiting traffic volumes based on aircraft operating criteria, such as noise levels, has a significant impact on traffic volumes and airport capacity.

Airport capacity.

An airport's capacity is determined by the number of flights and/or passengers carried over a given period of time (usually a year). The main reason for setting capacity limits is to limit aircraft noise affecting those areas of the airport where there is a concentration of service staff and passengers.

At John Wayne Airport, the capacity limit for the number of passengers carried is set at 4.75 million people. in year. By 2005 it is planned to increase it to 8.4 million people. in year. The number of actual operations is a more flexible value and is based on the sound energy emitted.

Airlines are not allowed to increase traffic in the future unless the airlines introduce quieter aircraft. Traffic volumes may be increased provided that 43.9% or more of the intended operations are classified as low noise, or the airport's noise standards are met. This somewhat controversial noise abatement policy is being reviewed by the US Federal Aviation Administration. According to US authorities, local airports can set noise limits as a reasonable means of achieving their noise reduction goals. However, such restrictions should not create serious obstacles to the development of interstate air services and international economic relations. Noise restrictions themselves cannot be unjustifiably discriminatory.

Land engine racing.

Many airports are equipped with devices designed for the routine maintenance and repair of aircraft. An integral element of this process is the mandatory conduct of static tests of engines at certain thrust or power modes.

Additional sources of noise may include auxiliary power units, power supply units, and other auxiliary equipment. Such races, depending on the location, time of day, type of aircraft and equipment used, may result in adverse noise impacts in the area adjacent to the airport.

Most of the work associated with engine racing is done during non-flying hours. This means that intensive aircraft maintenance work often occurs at night or early in the morning, which in turn creates real inconvenience for the population of nearby residential areas. Ninety-four U.S. airports have imposed noise restrictions on overhead engine races.

Aircraft towing.

Towing aircraft to reduce noise exposure is not a commonly used procedure, although it is commonly used during aircraft engine maintenance and repair work. Aircraft are towed to a dedicated stand for engine ground racing with all systems shut down prior to testing, which also reduces fuel costs. This raises problems associated with the risk of damage to the chassis and other auxiliary systems. In the United States, this method of noise reduction is no longer practical. Nevertheless, a return to this method is possible, which is completely determined by the ratio of benefits and costs when solving problems of safety and reliability, energy, and noise reduction.

Noise charges.

The administration of a number of European airports takes the lead in establishing noise charges. This approach is based on the principle that aircraft operators pay, in separate charges, an amount proportional to the noise generated by the aircraft.

5.3 Rules governing land use near airports

General airport development plan.

The general plan, usually classified as a structural or master plan, is usually official document, which is discussed and accepted by the local government. This plan is a guiding political document when addressing development issues in a particular area and regulates land use. Such plans are long-term in nature and are designed for 10-20 years.

The general plan covers issues of private land use, placement of public buildings and installations, as well as the development of transport links. All three of these elements predetermine the solution of land use issues, taking into account various interests and possible consequences for the environment. Considering noise generated in residential areas, along with other environmental factors, is an important part of effective and comprehensive planning.

The general urban development plan should take into account not only existing, but also future interests of airport development. The airport development master plan should be an integral part master plan development of this area. Both of these plans, unfortunately, are often developed independently of each other. Land use recommendations that take into account the overall interests of airport development, based on actual noise levels generated, are being developed in the United States for both military and civilian airfields.

Selecting the location of buildings.

It is important that when selecting an area for construction that could potentially be subject to the adverse effects of noise, measures are taken to reduce it. This approach, in turn, requires the approval of a certain procedure for discussing the relevant project in public organizations in order to properly take into account, along with other environmental factors, and the subsequent inclusion of provisions regulating the land use planning process. In such a procedure, it is necessary to consider the siting of buildings and measures to use natural or artificial acoustic barriers. However, it should be emphasized that a formal process that regulates noise control requirements at the government level is not yet widespread.

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11. Measures to combat noise problems.

Noise protection equipment is divided into collective and individual protection equipment.

Measures to reduce noise should be included at the design stage of industrial facilities and equipment. Particular attention should be paid to the removal of noisy equipment to a separate room, which allows reducing the number of workers in conditions of high noise levels and implementing noise reduction measures with minimal costs,

equipment and materials. Noise reduction can only be achieved by silencing all equipment with high noise levels.

Work on noise reduction of existing production equipment in a room begins with the compilation of noise maps and noise spectra of equipment and production premises, on the basis of which a decision is made regarding the direction of work.

Combating noise at its source - the most effective way to combat noise. Low-noise mechanical transmissions are being created, and methods are being developed to reduce noise in bearing units and fans.

Architectural and planning aspect of collective noise protection is associated with the need to take into account noise protection requirements in planning and development projects for cities and neighborhoods. It is expected to reduce the noise level through the use of screens, territorial breaks, noise protection structures, zoning and zoning of sources and protection objects, and protective landscaping strips.

Organizational and technical means of noise protection are associated with the study of noise generation processes in industrial installations and units, transport machines, technological and engineering equipment, as well as with the development of more advanced low-noise design solutions, standards for maximum permissible noise levels of machines, units, vehicles, etc.

Acoustic noise protection are divided into means of sound insulation, sound absorption and noise mufflers.

12. Electromagnetic field and man.

An electromagnetic field is a special form of matter, which is an interconnected electric and magnetic field.

The effect of electromagnetic radiation on the human body is mainly determined by the energy absorbed in it. It is known that radiation falling on the human body is partially reflected and partially absorbed in it. The absorbed part of the electromagnetic field energy is converted into thermal energy. This part of the radiation passes through the skin and spreads in the human body depending on the electrical properties of tissues (absolute dielectric constant, absolute magnetic permeability, specific conductivity) and the frequency of oscillations of the electromagnetic field.

In addition to the thermal effect, electromagnetic radiation causes the polarization of molecules in human body tissues, the movement of ions, the resonance of macromolecules and biological structures, nervous reactions and other effects.

From the above it follows that when a person is irradiated electromagnetic waves The most complex physical and biological processes occur in the tissues of his body, which can cause a disruption in the normal functioning of both individual organs and the body as a whole.

People working under excessive electromagnetic radiation usually get tired quickly and complain of headaches, general weakness, and pain in the heart area. Their sweating increases, irritability increases, and their sleep becomes disturbed. In some individuals, with prolonged irradiation, convulsions appear, a decrease in memory is observed, and trophic phenomena are noted (hair loss, brittle nails, etc.).

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With such development of transport, it is not surprising that noise pollution of the environment has constantly increased.

2. State of the problem of reducing transport noise

The use of a particular method or combination of methods depends largely on the extent and nature of the noise reduction required, taking into account both economic and operational constraints.

Any attempt to regulate noise must begin with identifying the sources of that noise. Despite the presence of significant similarities between various sources, they are quite dissimilar from each other for three modes of transport - road, rail and air.

3. Limiting exposure to road transport noise

3.1 Reducing traffic, improving road design and regulating land use

In large and small cities where bypass routes have not yet been created, you can switch traffic flow at night to the streets where commercial enterprises are located.

Success in reducing speed can be achieved by installing raised areas on the road surface or transverse stripes on the road, which allow drivers to feel the speed of the vehicle. Other methods include narrowing the road and bending the road alignment.

Road design.

The noise emitted by motor vehicles depends on both the vertical and horizontal outline of the road, as well as the type of road surface.

In addition, the construction of the barrier must be economical.

Cut roads are usually well shielded by the edge of the shield wall, although reflections from a distant wall may reduce the shielding performance.

On roads located on an embankment or overpass, noise problems are more severe, although some shielding does occur at sound pickup points located below the edge of the embankment or parapet.

Calculation of road intersections.

Important, from the point of view of limiting noise, is, apparently, the structure of the road surface itself; whether it is formed by a bituminized material with a random structure pattern, or a concrete coating with a dominant transverse structure.

Some road surfaces combine low noise and satisfactory lateral skid resistance characteristics. Such road surfaces usually have a porous structure that is moisture permeable, but at the same time has satisfactory sound absorption in the frequency range from 400 Hz to 2 kHz.

Land use planning.

The physical characteristics of walls that contribute to good sound insulation are low rigidity, high damping levels and high mass. Thus, a thick stone wall will have higher sound insulation than a thin glass panel.

Noise generated by road traffic often has high levels in the low frequency range, where the sound insulation of the building envelope is usually determined by the mass of the building envelope.

4. The problem of reducing noise from railway transport

Perimeter rule.

This rule is used to limit the range of flights carried out when departing from a given airport. Flight range can affect noise levels in a variety of ways.

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11. Measures to combat noise problems.

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