Modeling the dependence of the noise level on the speed of vehicles

. In this research work, the analysis of the noise level emitted by vehicles on the streets of the city of the following objects located around the public roads of Tashkent city: Kushbegi, Koshkurgan, Nukus, Altintepa, Temur-Malik, Beshqayragoch streets is presented. Based on the data obtained as a result of natural experiments, the laws of the impact of vehicle movement speed, speed, and composition on traffic noise were determined, according to which a program was developed to find the value of the noise level using the values of the vehicle weight and movement speed in the developed model.


Introduction
Dealing with noise, which is one of the factors that have a negative impact on the environment, which significantly changes its condition for the worse, is becoming a priority for improving the global environmental situation. It is known that the main sources of noise in cities are road noise. Noise causes severe damage to the human body when it interacts with other unpleasant factors, such as vibration, dust, smoke, and gas. European scientists have proved that the increase in the number of nervous, heart and wound diseases in the second half of the 20th century can be directly related to the impact of noise on city residents. Noise is a chaotic mix of different noises. The waves created by the vibrations of the sound-emitting body spread in the air, sometimes making the air denser, sometimes thinner, resulting in sound pressure. Noise has a negative effect on nerve fibers, can cause "noise disease" in addition to neuritis of the nerves [4,6,9]. At present, a lot of practical experience has been accumulated on the use of various measures to reduce noise. Tens of thousands of kilometers of acoustic screens have been installed in Japan, the USA, Germany, Italy, Canada, Australia, Sweden and other countries. Japan, France, and Germany use noise-absorbing road surfaces to reduce tire noise.
Embankments and green spaces have been successfully used to reduce noise levels in the way of sound propagation. The development of the noise protection complex is carried out in accordance with the required level of sound reduction, and the selection of screen structures is made, first of all, taking into account the effectiveness of noise protection measures and their cost, as well as safety requirements, operational characteristics and aesthetic perception.
As a result of urbanization in large cities, the need for public and private transportation is increasing along with the population growth. As a result, a number of economic, social, ecological, sanitary-hygienic conditions are aggravated, such as a decrease in the capacity of the streets, a decrease in the speed of vehicles, the occurrence of traffic jams at most single-level intersections, loss of time for passengers, as well as an increase in exhaust gases and traffic noise.
The city of Tashkent is relatively new -despite the fact that most of the requirements of urban planning are formed according to the requirements of current norms, today, in this city, the issue of pedestrian and vehicular intersections, along with the issues of providing parking lots and garages for private cars, is a sharp increase in the number of vehicles. as a result, the level of pollution of the sanitary condition of the city from traffic noise is also a separate topic.
The optimal solution to the issue of transport in urban planning is formed on the basis of multi-factor analysis, in which complex economic, social, sanitary-hygienic, ecological issues need to be rationally solved. Because the prospective development of this master plan of the city is determined by the previously adopted solutions. As the indicator of the development of transport infrastructure is manifested as a form of urbanization, the relevance of the issue of transport, especially in large cities, is increasing accordingly.
It is known that the existing street-road network in cities is evaluated by its density index. The density of the street network is determined by the ratio of the existing network length (km) to the total area of the city (km2). Therefore, the carrying capacity of the street-road network depends on its density index. As measures to increase the capacity of the street-road network, using two-and multi-level artificial overpasses, which are used in developed countries, to organize intersections at different levels, to connect the main transport nodes of the city (international and local stations, airports, etc.) There are experiences such as connecting, building multi-storey car parks and extensive use of the underground environment in this area. The problem of transportation in urban development has become a very urgent issue, especially in large cities, in particular in Tashkent. Although the density of the street network in the city of Tashkent, which has grown almost four times in the last hundred years in terms of territory, is relatively better than the situation in the world's major megacities, it does not meet the requirements for the capacity of the network [15]. Therefore, two and more level overpasses are being built to increase the capacity of the largest intersections. Such works will increase the density of the road network and the capacity of the network. However, the issue of vehicle noise in the city street-road network has not lost its relevance as the main issue causing discomfort in the urban environment. Disruption of city sanitary-hygienic conditions due to traffic noise, especially in large cities, requires the use of special noise-absorbing screen constructions. In developed countries, the use of special noise-absorbing screen constructions is widespread.

Materials and methods
The calculation methods analyzed in the scientific research are based on some interesting scientific developments carried out in Japan [1,12,13] and Russia [6,11], as in the classical theory of noise propagation in space [11]. In order to perform calculations for noise measurement, a classification of the main calculation schemes presented in Table 1 has been developed. The proposed calculation schemes are based on the specific characteristics of sound propagation in residential buildings [6,7]. It is known that the main sources of noise in cities are road noise. When measuring the level of noise on public roads surrounding urban settlements, it is carried out on the basis of GOST 20444-85 and GOST 23337-2014, valid for the regions of our republic, during the fast movement of traffic in the selected object (street-road network), the residential areathe facade of the house. A special noise measuring device and a device microphone are installed at a distance of 2 m from the front facing the direction of the traffic flow. The noise level is measured for a minimum of 20 minutes and a maximum of 30-40 minutes. The noise equivalence level of the transport flow is expressed by L_eq, DBA [7]. In order to measure traffic noise, it is desirable to measure the "peak time" of the highway.
The noise of the city streets is a chaotic mix of different noises. The waves generated by the vibrations of the sound-emitting body spread in the air, sometimes making the air denser, sometimes rarefied, resulting in sound pressure. But in cities, the main part of them is noise from motor vehicles [3,9,14].
in time interval allowed norm noise pitch dBA     The results of the conducted natural experiments show that according to No. 0008-20 "Sanitary Norms and Rules" [8] developed by the Ministry of Health of the Republic of Uzbekistan, the permissible daytime noise level in the streets of Kushbegi, Koshkurgan, Nukus, Altintepa, Timur Malik in Tashkent it was determined that the maximum 21 dBA and the minimum 10 dBA are more than the permissible sanitary norm (55 dBA). In this study, the speed of passenger cars was studied, and it was observed that the noise level increases as a result of increasing the speed of the car every 5 and 10 km/h. We check whether the obtained results correspond to mathematical laws by setting the correlation coefficient to the specified value. We find the linear regression equation of noise pressure level (L) versus velocity (v). where n is the sample size of a random value n=15. For this, we construct the following system of normal equations found by the method of least squares.
Using the values given in Table 2 Therefore, the following linear equation model of "L" as a function of speed "v" was developed: ^= 0, 2 + 49, 9 We check the adequacy of the found model: Correlation coefficient: = 0, 986 Now we estimate the correlation coefficient. In this case, we use Student's t-sign. We find the empirical t_emp and critical t_crit values of t: At the significance level of a = 0.01 k=n-2=15-2=13, when the degree of freedom is equal to 13, we find the value of t_crit from the MS Excel NORMSTOBR function:
Thus, a linear model between v and L was found, and the adequacy of the module found using the least squares method was determined using Student's t-test and Fisher's Z-substitution.

3
The results and discussion The minimum and maximum increase of the noise level above the permissible norm (55 dBA) during peak hours of the day on the streets of Kushbegi, Koshkurgan, Nukus, Altintepa, Temur-Malik, Beshkayragoch, located around the Khalka roads, is as follows: • • Despite the fact that the density of the street-road network of the city of Tashkent is increasing, the level of loading of this street is very high (more than 2400 cars/hour in each direction); • Most of the 95% of motor vehicles in motion are passenger cars; • According to the results of the research, the laws of the impact of speed, speed, composition and weight of motor vehicles on traffic noise were determined; based on the laws of dependence of the factors affecting the traffic noise, the traffic noise forecasting model was improved.

Conclusion
In this research work, the deterioration of the sanitary conditions caused by traffic noise on the streets of Tashkent, the reasons that cause them, were studied based on clear evidence, and the priority directions for solving problems in the transport system and the problems caused by traffic on the city streets were studied in detail and general conclusions can be drawn.
• The level of noise emitted by motor vehicles along the construction line on Tashkent Khalka roads and Kichik Khalka roads is higher than the sanitary norm of 55 dBA at peak times; • to bring the noise level to a sanitary norm, it is recommended to use special noise-absorbing screens on this street The use of noise-absorbing screens today in urban planning provides a number of optimal solutions, in particular, the use of land resources considered valuable in urban planning, architectural and aesthetic appearance of the area, very high noise absorption efficiency (compared to basic engineering activities), acceptance as a new construction as an element of modern urban planning possible;