Evaluation of public spaces street activity for its sustainable planning and design

. In the context of rapid urbanization and increasing population density, the role of city streets as public spaces in cities is increasing. Street space activity is measured in terms of the number of functions it can offer users. The urban space of the streets plays the role of social services for the population, a linear element of the green frame of the city and a business center, which corresponds to the three aspects of sustainable urban development. Thus, the intensity of use of public spaces becomes an indicator that characterizes the sustainability of the development of the city as a whole. The article presents the results of a functional analysis using the methods of spatial analysis and field observations of public life, carried out on the streets of Moscow. Data processing using statistical methods will make it possible to distinguish three types of streets with different characteristics of the functional content.


Introduction
A city is a complex dynamic system whose main purpose is to provide life being of the population. A street and road network are one of its subsystems and with the linear framework that ensures its urban spatial coherence. However, in the environmental scale, urban streets represent the public space of a modern city as the concentration and reflection of the relationship between the characteristics of a particular territory and the public behavior of people. The impact of an urban street area on social processes in the city and population behavior in such a space depends to a greater extent on the infrastructure placed there. Urban streets are considered to have a predominantly transit function and a secondary transit function for pedestrian traffic. Modern trends dictate another role, in which the street is a public space, and the transit function of various vehicles and pedestrians becomes only part of the process.
The article considers the use of the pedestrian part of the street, which performs a range of functions -economic, ecological and social, providing a city sustainability.
Ecological functions are provided in the form of urban street landscaping. Their type ranges from lawns on strips separating the carriageway and pedestrian part to squares and boulevards as separate types of green streets. Also, the environmental issue includes the collection and reuse of surface water and various types of pollution: carbon and other gas emissions, noise, vibration, dust and others. In this article, this issue is addressed only superficially in the framework of proposals for the organization and improvement of pedestrian spaces.
The object of the study in the article is to coordinate the economic and social functions of the method of spatial organization of territories. Businesses placed on or along pedestrian street spaces work for the social service of the population. The laws of the market and competition produce a selection of those types of business activities that are demanded by the population. From an urban planning point of view, the question is if there is a correlation between the location of the street in the city and the geometric characteristics of the space and those business activities that are located on it.
The preliminary phase of the study also highlighted the diversity of uses of pedestrian spaces on city streets. There are basic needs that can be realized in the pedestrian spaces of urban streets -pedestrian transit, transport services, and a range of related services. At the same time, there are streets that are multifunctional public spaces with cafés, co-working spaces, recreation areas and many other functions.
The formation of public spaces in cities is the topic of many authors-researchers' work. Public spaces as the basis of social life of the city is considered in the works of N. Lefebvre, B. Jałowiecki [1,2].
The analysis of the laws of formation of public spaces are presented in the works of T.S. Batalina, P. Lorens, D. Kochanowska [3,4,5].
In the works of M. Kohn, J.S. Kayden, P.
Hall give examples of models of improvement of public spaces [6,7,8].
In the studies of D.Harvey, A. Amin propose different approaches to assessing the quality of public spaces [9,10].
Peculiarities, problems and prospects of street retail development are also paid a lot of attention in economics in the works of such authors as A.H. Maslow, L. Dowell, O. Newman [17,18,19].
Common to all these works is that all the researchers agree on the need to improve the use of public spaces through economic, environmental and social requirements.
On the other hand, their analysis of the works let us discover our own niche for the study at the junction of urban planning and the urban economy. Our study's scientific problem is to find the regularity between business development on city streets and their planning solution.
Thus, the aim of the study is to find interconnections between the planning solution of city streets public spaces and the number of different types of activities demanded by the population.
The objectives were to analyze the existing experience of the organization of public spaces of urban streets on the example of Moscow, as well as to identify their typology by the criterion of their active use.

Materials
The study materials are streets in the city of Moscow as an example. Moscow has a unique experience of urban streets improvement as part of the city program. In the design solutions of the streets are implemented modern approaches to the organization of public spaces. Their content and nature of use, which allows using these streets as experimental.
For the study we chose sections of the public spaces of the city streets with the boundaries from intersection to intersection ( fig.1) on one side. The street as a whole was regarded as the sum of the sections. • streets that have undergone an improvement procedure; • location in the public-business part of the city; • high volume of pedestrian traffic.
The street segments selected according to these criteria serve as a benchmark for the development of a typology of public spaces according to the degree of their active use.

Methods
The research methodology includes several methods at different stages of the research and is presented in the figure 2.

Fig. 2. Research methodology
The experiment was set up using a systems analysis method to provide a holistic view of the problem. The method used for data collection is the field survey method, in order to obtain up-to-date information on the object content, intensity of use and the nature of pedestrian behavior.
The street-level data processing aims to identify and confirm the boundaries of typical groups in terms of the degree of public space use activity on city streets. The criteria for assessing the activity of the use of public spaces of the city streets are: • presence/absence of commercial enterprises; • presence/absence of accomplishment elements; • presence/absence of transport-pedestrian and engineering infrastructure. • Quantitative characteristics that describe pedestrian behavior include: • intensity of pedestrian / bicycle / SIM traffic; • speeds of individual groups of traffic; • the width of public space used for different purposes.
Based on the proposed criteria and parameters, a typology of urban streets is carried out according to the activity of using public spaces of urban streets.

Results
Based on the study of cartographic material and visual assessment of the urban environment, 12 streets of Moscow were identified consisting of 91 plots with different subject-spatial content, as well as different nature of use.
In the course of on-site surveys, the main surveyed elements were recorded. located on each section of the city streets. these included commercial enterprises, accomplishment and transport and pedestrian infrastructure elements. Their list is presented in the table 1. As the result it was found that each section of the urban street has a different object content and a variety of human behavior in it.
The analysis of the object content showed that the most common object content is: • pedestrian sidewalk providing human movement; • elements of service infrastructure -lightning, drainage, garbage bins, etc.); • landscape elements (lawn, flowers, bushes, trees). The rest of the content is present point-by-point in different parts of the city streetsplaces for pedestrians to stop and rest or various services that provide different types of services.
Further analysis of the distribution of the placement of different infill facilities on urban street segments has enabled them to be divided into three main types based on two main characteristics: • the set of elements to be placed; • the intensity of the use of public space.
The intensity of the use of public space was evaluated using the following gradation: • long time stay more than 15 min -a person's long-term stay in a city street to receive various types of services; • short time stay less than 5 min -stopover -a short-term stay of a person on a city street to receive a certain type of service; • transit or short time stay (less than 5 min) -transit traffic or only minute waiting stop. The analysis has made it possible to establish a relationship between the types of use of the street area and the businesses located in the adjacent development and the nature of the behavior of the population, according to the matrix shown in Figure 3.

Fig. 3. Street elements presence evaluation
Statistical processing of the results allows us to conclude that the set of elements that make up public space and their number will determine the possibilities for human action in it, thus setting different properties of the space.
Commercial businesses are located along the street boundaries, but have activities that occupy the street space. Thus, they participate in an active long-term or medium-term human presence on the street -restaurants, cafés, food street, vending machines and other services. The operation of these types of businesses has an impact on the street width -to the usual pavement for transit traffic additional space is needed to organize activities other than direct traffic.
In addition, additional space is required to accommodate other infrastructure typical of urban public spaces: • small architectural forms -functional, symbolic; complementary in giving content to the space; • elements of transport and engineering infrastructure are utilitarian and have a pronounced connection with the city system; • landscape elements -flower beds, lawns, trees, are indicators of the ecological character of the space. Thus, according to the results of the study based on the analysis of the intensity of the use of public spaces, the analysis of the object filling and functions, the analysis of the social characteristics of public space, three types of public spaces of city streets are derived: active street, medium active street and transit street. Their description and main characteristics are presented in the table 2. An active street is a linear public urban space. It is saturated with a variety of human activities. Figure 4 shows the composition of the different activities recorded during the study. It should be noted that active streets are certainly wider than other street types, but they can also be very compact, such as Nikitskaya Street in Moscow, which is located in the very center.
Middle active streets perform mainly a transit function, but provide related services to the public. These are mainly transport services, providing entrances to adjacent shops or transit services such as street food or scooter or scooter rentals. Their width is calculated from the intensity of the passing pedestrian traffic, taking into account the necessary areas to accommodate service points. An example of the composition of street elements is shown in Figure 5. In the photo you can see how the transit character of the street is emphasized in the direction of tile paving. However, there are also public realm elements of landscaping, a bus stop and building entrances. Transit streets are the simplest type of street that is designed for transit traffic only. However, even this linear space can be equipped with landscaping elements, but only if there is room for comfortable and safe direct traffic. A typical composition of the elements is shown in the figure 6. Also, you see an example of a transit street.

Conclusion
The study of public space provides quite diverse information about the specifics of society's functioning, its values, priorities and orientations, level of integration and development. Summarizing the material presented in the article, we note the following: 1. Public space is an important and promising object of scientific study. Obviously, in the dynamic and changing modern society, researchers are particularly interested in the changes taking place in the social environment -in social relations, communities, institutions. And it is quite natural that these changes should be reflected in a certain way in the public space -in its very organization, in its functional purpose and peculiarities of public use.
2. Urban streets as a part of public space play an important role in sustainable urban development by fulfilling a range of social, economic and ecological functions. The proposed typology gives an idea of the type of streets, which is a necessary step to select and justify design solutions.