Gazebo-Type Small Architectural Form as a Noise Protection Structure for Residential Area Improvement Sites

Introduction. The implementation of national projects aimed at the development of transport and housing infrastructure increases the requirements for the quality of urban environment, as well as for the safety and comfort of courtyard spaces [1][2]. In these circumstances, the noise generated by vehicles is considered not only as an engineering challenge in road design, but also as sanitary and hygienic risk for the population.

It has been established in scientific literature that traffic noise is a significant component of physical pollution in urban areas and has an adverse effect on the quality of life and health of residents [3]. Generalized studies have linked prolonged exposure to noise to neurological disorders, cardiovascular diseases, anxiety, and other negative health effects [4–6]. Consequently, reducing the acoustic load in residential areas has a pronounced sanitary and hygienic, and urban planning significance.

Existing approaches to noise pollution control in urban areas can be divided into several categories. The first category includes engineering solutions, such as acoustic screens, enclosure structures, and sound insulation elements in buildings [8–10]. The effectiveness of these measures depends on factors such as height, position in relation to the noise source, geometric characteristics, material used, and the presence of sound-absorbing materials [11–13].

At the same time, engineering screens are not always the best solution for courtyard spaces. In reality, their use can be limited by various factors such as architectural, operational, sanitary, and economic considerations. Additionally, the actual condition of acoustic screens and the way they are placed can reduce their expected noise reduction effectiveness [14].

The second group of solutions involves the use of small and specialized acoustic screens [15][16]. These structures can reduce local noise, but their effectiveness depends on several factors, such as height, position relative to the noise source and receiver, and the type of traffic. Therefore, the results obtained for railway or mainline noise cannot be automatically transferred to courtyards and landscaping sites. Figure 1 provides a generalization of these screen solutions.

The third group of solutions involves using green spaces to provide noise protection. These spaces can have a sufficient width, density, and number of plants to perform this function [17][18]. The most effective form of this is an array of tall trees, complemented by shrubs. Vertical structure and density of the trees' crowns determine their ability to attenuate noise.

Existing or specially designed green spaces can serve as natural noise barriers. Studies have shown that their effectiveness depends not on the mere presence of landscaping, but on the structural parameters of the plants: height, density, strip width, number of levels, and presence of a shrub layer [17][18].

Consequently, green spaces have a significant ecological and urban planning potential. However, under conditions of limited courtyard space, their noise reduction effectiveness may be insufficient. The main challenges are related to the requirement for additional land, insufficient planting density, and the preservation of open canopy areas.

In practice, this can lead to a situation where landscaping enhances the appearance of a territory, but it does not always guarantee the achievement of noise levels required by regulations at the borders of recreational and leisure areas.

When placing guest parking spaces and local driveways near children's and sports areas, additional local safety measures are needed that are compatible with the architectural and planning design of the courtyard (Fig. 2).

This formulation of the problem allows us to consider SAFs as a potential element of the first line of defense against noise in regulated residential areas.

The analysis of these approaches shows that each of them has its limitations when used in high-density residential development. Traditional screens can worsen the visual appeal of the courtyard area and require additional design and construction costs. Green spaces require a significant amount of space and may not always provide adequate protection, even with an open canopy. Small acoustic screens can be effective in certain geometric situations, but their applicability is limited.

This issue is particularly significant for recreational and leisure areas that are located near local roads and parking lots. Under these circumstances, a local noise reduction solution is needed, which not only decreases the acoustic impact but also maintains the functionality and aesthetic appeal of the landscape area [7].

When it is difficult to install traditional screens or create full-fledged green or protective strips, design and maintenance companies can utilize continuous landscaping features such as retaining walls, enclosing structures or small architectural forms (SAFs) (Fig. 3). Their advantage lies in their ability to combine the protective function with landscape design.

From these perspectives, the use of landscaping elements as part of a noise protection system is a promising approach. Unlike special engineering screens, small architectural forms can simultaneously perform recreational, urban planning, and protective functions, which is particularly significant for small courtyard spaces.

However, existing research focuses on traditional acoustic screens, green spaces, and engineering noise-proof structures. The possibility of using small architectural forms with blind enclosing surfaces as local structures to protect landscaping areas from noise has not been sufficiently studied.

Despite the availability of research on traditional acoustic screens, green spaces, and small noise-proof structures, the potential of using functional landscaping elements combining recreational and protective functions as a means of local noise reduction in courtyard areas has not been fully explored. The scientific novelty of this work consists in the calculated assessment of a small architectural form with blind enclosing surfaces as a local noise protection element for recreational areas in residential areas and in comparing its effectiveness with traditional noise protection options.

This work aimed to estimate the potential of using small architectural forms with blind enclosing surfaces as local noise protection elements of landscaping (SAF) to reduce the noise impact of around the house infrastructure, primarily vehicles, on recreation areas and leisure areas of residential areas.

To achieve this goal, we have solved the following tasks:

1. We have analyzed possible noise protection solutions for residential landscaping sites.
2. We have prepared calculated noise protection options, including the absence of fencing, a typical noise barrier, green spaces, a small acoustic screen, and a gazebo-type SAF.
3. We have determined the initial parameters of traffic noise and the sound insulation characteristics of the SAF enclosing structure.
4. We have simulated noise propagation in the landscaping area and compared the calculated levels with the maximum permissible values.
5. We have conducted a comparative assessment of the options based on sanitary, ecological, urban planning, and economic criteria.

Materials and Methods. Empirical Base and Data Sources. The research was based on the data from regulatory documents, scientific publications, technical specifications of noise-resistant structures, as well as field route observations conducted on the territory of residential buildings. This information was used to develop design scenarios, define initial parameters of traffic flow, and establish criteria for assessing noise levels.

Specialized software, ecological Geographic Information System (GIS) “Ecolog-Shum” was used to conduct computational and analytical work to assess the acoustic load. The software package is included in the Unified Register of Russian Computer Programs and Databases, having been approved by the Ministry of Digital Development, Communications and Mass Media of the Russian Federation.

There were also additional modules of the software package:

– “Noise from Highways” module. It was used to calculate the equivalent (LAeq) and maximum (LAFmax) sound levels of the traffic flow. The methodological basis was provided by the relevant documents of the transport industry;

– “Sound Insulation Calculator” module. It was used to determine the air noise insulation index (Rw) of enclosing structures. The calculation was performed in the one-third octave frequency bands of 100–3150 Hz, followed by extrapolation to standard octave values. Additionally, when selecting criteria for evaluating the characteristics of materials, reference information from the electronic catalog of the Research Institute of Building Physics (1988) was used.

The rationale for the adopted acoustic models was based on current regulatory and technical documents of the Russian Federation and reference materials (see notes throughout the text and references).

The parameters of planned residential development facilities were taken from the previously developed design documentation.

Noise characteristics of vehicles were determined based on the traffic density recorded during field work in July 2025 on the territory of the projected residential neighborhood in Yekaterinburg. These works were conducted as part of engineering and environmental surveys for the pre-design study of project documentation and were aimed at assessing the actual noise level at the boundary of the planned landscaping site.

When developing recommendations for noise reduction, we used the maximum permissible levels (MPLs) set by the sanitary and hygienic standards for residential area facilities as a basis. We selected the characteristics of the proposed noise shielding, including the panel material, sound absorption coefficient αw, surface density, and other parameters based on the manufacturers' technical specifications, or taking into account proposed design solutions and background information.

GIS graphical interface allowed simultaneous editing of the parameters of sources and obstacles, including specified sound absorption coefficients and calculated points, both in tabular form and on a digital map. To create the noise map, a substrate from the design documentation was used and adapted using open geodata, which was imported through the GIS-Standard module in *.SHP format. The effectiveness of the measures was assessed by comparing “basic” and “design” scenarios: the “basic” scenario was before the introduction of protection measures, and the “design” scenario included the implementation of noise protection options that were considered.

Object of Research. A small architectural gazebo-type form with a solid back wall was chosen an object of research to protect landscaping sites from noise from local traffic (Fig. 3, 4). This design was analyzed as a local enclosing element that could partially perform the function of an acoustic screen.

Limits of Applicability of the Design Scheme. In this paper, we considered a special computational case involving the use of a small architectural form (SAF) in the form of a semi-enclosed gazebo with a blank back wall. The results were obtained based on the accepted planning diagram, the specified traffic flow parameters, and the selected configuration of the enclosing structure. To extend these conclusions to other types of SAFs, building options, and noise load scenarios, additional computational and field studies were required.

Calculation scenarios. To compare the effectiveness of noise protection solutions, five design options were set, differing in the type of enclosing or protective structure:

– option 0 — absence of any enclosing structure;

– option 1 — the use of a typical combined noise-proof screen: a noise-reflecting panel + a noise-absorbing panel + a noise-reflecting translucent panel, without a structural canopy; the sound insulation index of air noise was taken from technical data;

– option 2 — the use of double-row deciduous tree and shrub plantings; the attenuation of sound in octave bands when passing through dense foliage was determined by the length of the sound propagation path;

– option 3 — the use of a small noise shield; the effectiveness of a small acoustic shield, depending on the frequency, was accepted according to [16];

– option 4 — the use of a gazebo-type SAF with a solid back wall made of wood laths; the air noise insulation index was determined by calculation.

Table 1 presents brief initial data on the accepted options for enclosing structures.

Initial Sound Insulation Parameters of the Enclosing Structure. The calculation of airborne noise insulation for a single-layer flat thin screen was performed according to the algorithm given in clause 9.2 of SP 275.1325800.2016². The calculation was done using the “Sound Insulation Calculator” software (developed by Integral), which followed this method.

The frequency response of the air noise insulation of the SAF solid wall, considered as a single-layer flat thin enclosing structure, determined graphically and represented as a broken line, is shown in Figure 5.

Table 5 presents the calculation results of air noise insulation index RwR_w for the SAF back wall.

The data on the enclosing structure given in Table 2 was used as the initial data for the calculation.

Initial parameters of the traffic flow. To determine noise characteristics of the traffic flow, the calculation algorithm described in clauses 6.2.8–6.12.8 of SP 276.1325800.2016⁷ was used. The initial parameters included the estimated time of day, traffic density, share of freight traffic, speed, roadway slope, pavement type, and the presence of other road factors.

Software tools for calculating traffic noise. The calculation of traffic noise was performed in the “Noise from Highways 1.1” module (developed by Integral). This module allowed us to determine the equivalent sound level when traffic flowed under specified road conditions, considering the individual characteristics of the flow.

The initial data for calculating noise characteristics of automobile traffic flows are presented in Table 3.

Assessment Criteria. Software tools for noise propagation simulation. The simulation of noise propagation was performed using “Ecolog-Shum 2.4” (developed by Integral), which had the recommendations of the Research Institute of Building Physics (Certificate of Conformity ROSS RU.SP04. N00084 dated 05.03.2007). The complex allowed calculating noise pressure levels at individual points and at sites, taking into account the diffraction and reflection of sound from obstacles.

Calculated Assumptions. The assessment was based on the equivalent noise level (dBA), which took into account temporary unevenness of the noise exposure. However, when performing the calculations, we did not take into account the effects of sound absorption or shielding from reflected signals from nearby buildings, structures, and green spaces, which allowed us to consider the values obtained as the result of the accepted calculation scheme.

Computing Chain. The research algorithm included: 1) setting the research object and design scenarios; 2) determining the sound insulation characteristics of the enclosing structure; 3) calculating the noise characteristics of the traffic flow; 4) modeling noise propagation for each option; 5) comparing the obtained levels with the maximum permissible values; 6) comparative evaluation of the options according to the specified criteria.

Evaluation Criteria. Noise parameters characterizing the acoustic impact on the environment, the location of noise sources and enclosing structures were used as initial data for the calculation. Sound pressure levels were calculated in octave bands with geometric mean frequencies of 31.5–8000 Hz, as well as for equivalent LA sound levels.

The modeling took into account the following:

– Calculations were performed in a local coordinate system, with the OX axis oriented to the east and the OY axis oriented to the north, assuming ground level as 0.0 and without considering terrain. The minimum dimensions of the calculated rectangle were 70 × 70 m.

– The calculation considered the diffraction and reflection of sound waves by enclosing structures, taking into account meteorological parameters such as temperature and humidity.

– Equivalent sound pressure levels Leq during exposure time T were calculated based on octave levels and considering the duration of the time interval: daytime — from 7 to 23 hours, night — from 23 to 7 hours.

– The selected points were located directly on the territory of the adjacent residential area, in accordance with the requirements of SP 51.13330.2011¹⁴. For recreation areas of residential districts, groups of residential buildings, sections of preschool institutions, schools, hospitals, and sanatoriums, the points were chosen at the boundaries of the closest sites to the noise source, at a height of 1.5 meters above the ground.

The results were presented in tables and in the form of colored noise maps — isolines.

The normalized noise parameters for the considered territory — recreation areas and leisure areas of residential areas — were adopted according to SanPiN 1.2.3685-21¹⁵ (Table 4). The main criterion was the compliance with the maximum permissible equivalent sound level of 45 dBA.

Research Results. According to the accepted assessment procedure, the required calculations were conducted, the results of which are shown in the relevant tables and figures.

The frequency response of air noise isolation for the SAF solid wall as a single-layer, flat, thin enclosing structure is shown graphically in Figure 5 as a broken line.

The calculation results of air noise insulation index (Rw) for the SAF back wall are presented in Table 5.

Table 6 provides the calculations results of transport noise characteristics.

Table 7 provides the results of the noise propagation calculations.

The areas of negative impact from noise are represented by the isolines of the acoustic discomfort zones at a height of 1.5 meters (Fig. 6).

For visualization, a graphical distribution of noise in perspective (3D) was performed at a specified height of 1.5 m (Fig. 7).

Discussion. The calculated results indicated that the key factor in reducing noise levels at the border of the specified area was the presence of a solid enclosing surface between the noise source and the protected area. In this regard, options with a typical noise-proof screen and a gazebo-type SAF ensured that the maximum permissible level was achieved. However, without any enclosing structure, only green spaces and a small acoustic screen, in the current design scheme, did not lead to a comparable reduction in noise levels.

This interpretation was consistent with the literature data, which suggested that the effectiveness of acoustic screens was determined by their height, geometric parameters, position relative to the noise source and receiver, and the presence of a continuous shielding surface [11–14]. For gazebo-type SAFs, the noise protection effect was not due to landscaping itself, but rather to the presence of a blind back wall, which acted as a local barrier to sound wave propagation.

It should be emphasized that the results were calculated. While the software tools and regulatory techniques used allowed for a preliminary assessment of the acoustic effectiveness of the solutions analyzed, they could not replace instrumental verification under field conditions. Therefore, the noise reduction achieved for the SAF option should be regarded as a calculated and predicted value valid for the assumed geometry of the structure, the characteristics of the traffic flow, and the conditions of sound propagation.

To interpret the practical applicability of the considered solutions, a comparative assessment was conducted according to criteria reflecting not only the acoustic result, but also the possibility of using the appropriate measure in residential conditions:

– “Ensuring sanitary and hygienic standards” — compliance of the calculated noise level with the maximum permissible value for the normalized area;

– “Urban planning integration” — the possibility of including solutions in the architectural and planning structure of the courtyard area without compromising its functionality and visual perception;

– “Ecological effect” — the potential reduction of the negative impact of noise on the environment and living conditions of the population;

– “Material costs” — the estimated need for additional financial investments beyond the usual landscaping work.

This ranking indicates that the choice of noise protection measures should not be solely based on the magnitude of estimated noise reduction. Urban compatibility, operational feasibility, and the possibility of implementing a solution without creating a separate engineering structure are also important factors to consider for landscape sites.

Table 8 presents the comparative assessment results for the considered noise protection options.

The interpretation of the considered options demonstrated that a standard noise shield was the most obvious engineering solution, with the highest priority for achieving sanitary and hygiene goals. However, its use in the outdoor area could be constrained by aesthetic and planning considerations, as such a barrier would be perceived as a separate technical structure.

The low efficiency of the green space solution was explained by the fact that a strip 5–10 meters wide and an ordinary planting without a dense understory did not create a continuous acoustic barrier. This finding was consistent with data suggesting that sufficient width, density, and layers of plantings were needed to achieve a significant noise reduction effect [17][18].

The low efficiency of a small acoustic screen was due to its limited height. At 0.85 meters, this design did not block a significant portion of the sound path between the traffic flow and the design point at a height of 1.5 meters. Therefore, in the planning scheme under consideration, it did not guarantee the achievement of MPL.

The gazebo-type SAF option differed from the standard screen in that it combined the noise protection function with recreational and urban planning. This allowed us to consider such a structure not as a separate environmental protection facility, but rather as an element of landscaping that simultaneously created a protected space while preserving the functional purpose of the site.

The practical significance of the results obtained lies in the possibility of using a SAF with a blind back wall as a local noise protection structure, where traditional screens are undesirable or difficult due to architectural and planning constraints. However, further research is needed to fully assess the effectiveness of this solution for other geometric configurations and noise loading conditions.

The limitations of this study include the computational nature of the results, the consideration of only one type of SAF, one planning configuration, and one scenario for transport load. Additionally, the calculation method did not take into account certain factors of the urban environment, such as reflections from neighboring buildings and variations in actual traffic intensity.

Thus, the results should be interpreted as a calculated justification for the potential use of a gazebo-type SAF with a blind back wall for local noise protection. To verify the practical effectiveness, it would be necessary to conduct full-scale noise measurements before and after installing the structure, as well as perform a series of calculations at different distances from the source, considering traffic intensity and various building options.

Conclusion. The paper provides a calculated assessment of the possibility of using a gazebo-type SAF with a blind back wall as a local noise-proof structure for residential landscaping sites.

Based on the simulation results, it was found that with the specified parameters of the traffic flow, the option without protective measures did not ensure compliance with the maximum permissible noise level at the border of the specified territory. A typical noise shield and a gazebo-type SAF in the design scheme under consideration could reduce the noise level to 45 dBA.

Green spaces and a small acoustic shield under the accepted initial conditions did not provide the required level of noise protection, which was associated with insufficient length and/or height of the protective barrier.

The main conclusion of the research is that a semi-enclosed gazebo-type SAF with a blind back wall can be considered as a promising local noise protection solution combining acoustic and urban planning functions.

The results obtained require further verification through instrumental confirmation in field conditions and analysis of other types of SAFs and noise load scenarios to ensure accuracy.