THE PRACTICAL ASPECTS OF REDUCING THE LEVEL OF ACCIDENTS ON CITY ROADS BY FORMING A SAFETY PROFILE

of Kyiv, the main measures for the development of the city's street and road network are determined, taking into account the experience of the European analog.


РОЗВИТОК ТРАНСПОРТУ № 1(16), 2023
consequences on the example of the organization of the street and road network of European cities. The increase in the number of cars in the largest cities of Western Europe, which began in the 50s of the last century, followed almost the same pattern for all countries: a linear increase in the number of cars to the level of 300-350 cars/1000 inhabitants, then a slowdown in the growth trend and stabilization at the level of 550 ± 50 cars/1000 inhabitants [1]. A limit of saturation with individual cars was adopted, after which the level of motorization stabilizes, and only the rotation of the fleet takes place [2].
In order to find ways to ensure the effective functioning of the city's SRN, it is necessary to analyze the basic principles of improving the transport and operational qualities of city streets and roads, ensuring road safety, and increasing their capacity. To improve the efficiency of vehicles in the urban environment, the speed of cargo delivery and passenger transportation.
Research statement. Road safety is one of the main criteria for evaluating transportation systems. As a result, one of the primary tasks of optimizing transport systems is to improve road safety. A road is a complex dynamic system that includes a set of human-vehicle-road elements that operate in a certain environment. These elements are interconnected with each other and form an integrated transportation system. From the point of view of road safety, both the risk factors themselves and their various combinations are of interest for systematic study.
Literature review. It is known that about 75% of road accidents occur in cities, and more than half of them are concentrated in the areas of intersections of transport highways [3]. Therefore, the problem of traffic organization and safety is the most important urban planning task, the correct solution of which determines the reliability and quality of the entire urban transport system and the possibility of implementing the necessary engineering and technical solutions, including those to reduce the level of road accidents [4]. In different countries, scientists use far from identical methods of organizing traffic flows, as there is no general, universal solution to this problem. To ensure the safe passage of vehicles at any time of the year, it is important to constantly monitor the condition of roads, timely identify structural elements and areas requiring urgent repair, and a detailed assessment of traffic conditions of different densities. To perform these works, comprehensive road condition survey plans are required, which are used to develop measures to improve traffic conditions. Main part. Traffic flow is a complex system that includes vehicles, roadways and the environment, which includes all street and road arrangements and pedestrian traffic. The basic principle of the traffic flow system is the integrity of the traffic process, where the integrity of the flow is primary and the position and speed of vehicles in the flow is secondary [5].
The analysis of a priori information and technical and legal documentation allowed us to conduct a systematic analysis of the interaction of the components of the TFC and the factors influencing the safe organization of traffic (Fig. 1). This served as the basis for the formation of the conceptual principles of the safety profile to identify the causes of road accidents and reduce the occurrence of dangerous situations on the roads.
Research has shown that such scientists as Guk V.I. and Stepanchuk O.V. [6,7] suggest that the main reasons that reduce traffic safety are a few characteristic features of the road and traffic flow, such as insufficient width of the roadway; insufficient visibility; sharp unexpected change of road direction; intersection with unregulated traffic flow; lack of acceleration and braking lanes; bus stops without smooth adjacencies to the roadway; steep ascents and descents, etc. Statistical information on road accidents provides a fundamental opportunity for a comparative assessment of the degree of traffic safety under different parameters of the road elements and traffic intensity on the road. Thus, the parameters that significantly affect the situation during traffic and ensure safety can be represented as a triad of individual street and road network systems and road users (Fig. 2). This analysis was the basis for the formation of the traffic safety profile.
An analysis of the number of accidents on Western European roads showed that their number is lower than in Ukraine. Therefore, we will compare similar sections of the urban road network and their operating conditions.    As the main criteria for the comparative analysis of traffic organization at the junctions of the urban road network in Kyiv (Ukraine) and Rzeszow (Poland), several parameters of the street and road network and the road transport system were considered, which are given in Table 1 [8,9].
In accordance with the methods [9,10], based on the data in Table 1, we calculated and analyzed the quantitative indicators of traffic flow in Kyiv (Ukraine) and Rzeszow (Poland). The initial data and their corresponding calculation coefficients, traffic conditions at each of the intersections and adjacent streets, and the ranges of calculations under different traffic conditions were considered. In addition to the geometric parameters of the street and road network, a number of other parameters were considered [11].
The quantitative indicators of the triad are presented in Table 2, which makes it possible to evaluate and compare their values.
The essential elements of influence on the situation on the road by road users are primarily the composition of the traffic flow. The analysis of traffic flow on the city streets of the studied cities of Ukraine and Poland showed that there are differences in the types of vehicles and their technical and operational characteristics, which differ significantly from each other. Therefore, its composition plays an important role in shaping traffic conditions. The share of mass passenger transport on main city streets is 3-25%; trucks 2-15%; cars 60-95% [12,13]. Such a range of changes in indicators depends on a number of factors, namely: time of day, day of the week, city district and its main function. The real traffic flow has a stochastic nature of movement, which depends on random changes in the traffic situation and individual characteristics of vehicle drivers, so the capacity of the street and road network is subject to statistical patterns of traffic flow.

РОЗВИТОК ТРАНСПОРТУ № 1(16), 2023
To analyze and calculate, we selected statistical data on changes in the dynamics of the traffic situation over time on identical sections of the SRN in Kyiv and Rzeszow (Fig. 3). Monitoring of quantitative indicators of traffic flow made it possible to obtain average statistical data and, using mathematical dependencies, to model their change within 24 hours for both options.
When determining the quantitative indicators of traffic flow, the presence or absence of traffic control devices, pedestrian crossings, safety islands, adjacent buildings, parking spaces and the degree of infrastructure development, location in relation to the city center, and population density in the area were taken into account.
The structural elements and parameters of the street and road network of the study sites and the condition of the roadway made it possible to evaluate and verify the results of the calculations and their adequacy in practice.
It is impossible to completely prevent accidents, as the causes of accidents are not only unfavorable road conditions, but also the influence of many factors that relate to  both traffic conditions on the road and the impact of the traffic flow itself, an individual car, the human factor (drivers and pedestrians), weather conditions, etc. [14]. Based on the results of the calculations, a comparative analysis of the experimental sections of the SRN was carried out and the hazardous areas were identified. The risk assessment of road accidents considers the analysis of critical points on the road sections and decision-making to increase their level of danger. The identified critical points take into account the peculiarities of vehicle movement. The study of the SRN section in Rzeszow (Fig. 4a) showed that the most dangerous places are the intersections of traffic flows 1, 2, 5 and 1, 6, 7. These locations are shown in Figure 4a.
As for the Kyiv SRN section, which corresponds to the indicators of the Rzeszow SRN section (Fig. 4b), the critical points are the intersection of the 2nd, 3rd, 4th and the distribution point of the 1st traffic flow. The calculated indicators were confirmed by practical observations [15].
At each of the SRN nodes, the safety profile triad was evaluated and the dynamics of changes in the level of traffic safety at speeds from 10 to 80 km/h was calculated. This range was chosen based on speed limits, terrain and design features of the SRN in these areas. The calculations did not take into account static indicators, such as the design parameters of the SRN, but only dynamic and psychophysiological (for the driver). Based on the data in Tables 1 and 2, we mathematically processed the criteria presented in Table 3, which are the components of both vehicle trajectory safety and traffic flow.   Based on the data in Tables 1 and 2, we mathematically processed the criteria presented in Table 3, which are the components of both vehicle trajectory safety and traffic flow.

а) Intersection of Y. Pilsudskoho Avenue and A. Aznuka Street b) Intersection of Chokolovsky Boulevard and Aviakonstruktora Antonova Street
The analysis of the research results and calculations showed that the numerical values correspond to the permitted speed limits on the studied sections. For example, calculations are presented at a speed of 50-60 km/h in accordance with the regulated speed limits on the sections during the day. The results of the calculations for the main and secondary roads in both cases and their difference are within the normal range, and the calculated value of the braking distance (S t ) corresponds to the designed values.
The values of the actual throughput (N ф ) and the calculated throughput taking into account unfavorable situations and emergency braking (N max , N max ) do not exceed the permissible values, and therefore no structural changes are required at the existing SRN nodes, only organizational measures are needed to regulate traffic flows at the junctions (for regulated intersections) and within a block distance from the intersection (for unregulated intersections) and the use of GPS beacons to respond quickly in case of emergencies or to inform road users about the situation on this section of the road, which is quite relevant during peak hours. The speed limits are justified for this range of vehicle movement (50-60 km/h). However, calculations and observations have shown that increasing the speed to 70-80 km/h leads to accidents on both sections, which in 65% of cases are caused by the human factor and psycho-physiological characteristics of drivers.
According to Table 3, other calculations were carried out in the range of 10-80 km/h. The mathematical dependencies of changes in traffic flow indicators -throughput and average speed -allowed us to graphically assess their dynamism (1): The values of the actual throughput (N ф ) and the calculated throughput taking into account unfavorable situations and emergency braking (N max, , N max ' ) do not exceed the permissible values, and therefore no structural changes are required at the existing SRN nodes, only organizational measures are needed to regulate traffic flows at the junctions (for regulated intersections) and within a block distance from the intersection (for unregulated intersections) and the use of GPS beacons to respond quickly in case of emergencies or to inform road users about the situation on this section of the road, which is quite relevant during peak hours.
The speed limits are justified for this range of vehicle movement (50-60 km/h). However, calculations and observations have shown that increasing the speed to 70-80 km/h leads to accidents on both sections, which in 65% of cases are caused by the human factor and psycho-physiological characteristics of drivers.
According to Table 3, other calculations were carried out in the range of 10 -80 km/h. The mathematical dependencies of changes in traffic flow indicatorsthroughput and average speed -allowed us to graphically assess their The graphical interpretation of the calculation results showed that on the studied sections of the SRN (Fig. 5, Fig. 6 The graphical interpretation of the calculation results showed that on the studied sections of the SRN (Fig. 5, Fig. 6) there is a clear decrease in traffic capacity when leaving the junctions and intersections. The maximum throughput values are achieved at traffic speeds of 35-45 km/h. The analysis of the graphs showed that there is a direct proportional relationship between the average speed and traffic capacity at road junctions and intersections. In this case, the presence of traffic lights and other means of traffic management can be ignored.
In the calculations, 80 km/h was proposed as the maximum value of the speed range, because, despite the design and parametric features of the studied sections, the time intervals when the car can move with a higher value on the speedometer are minimal in relation to the total time used for the calculations.
Conclusion. The result of mathematical processing allowed us to confirm compliance with the designed requirements for the qualitative and quantitative indicators of these transport nodes of the city's street and road network.

РОЗВИТОК ТРАНСПОРТУ № 1(16), 2023
As an indicator of the effective organization of traffic flows is the minimum value of peak conditions and accidents. Therefore, the traffic safety profile took into account the experience of Western European countries to improve the level of vehicle safety. The analysis of statistical information [2,7] on the causes of traffic accidents showed the awareness of all categories of users of the SRN due to technical means of traffic organization and modernization of existing elements of the traffic management system. This helps to reduce accidents, but cannot completely eliminate the peculiarities of the psychophysical state of the population, both on the part of drivers and pedestrians in real time.
Conclusions. As the practice shows, the modernization and reconstruction of road traffic facilities is not always feasible and economically justified. Therefore, the formation and analysis of a traffic safety profile will help identify the most effective solutions to reduce road accidents and hazards in urban areas. One of the most effective means is to develop not the entire city network, but only its information component and communication between its elements.
Thus, the rational use of the existing transport network to improve the safety of the SRN includes such measures as the distribution of transport by lanes and adjacent streets and highways to optimize road congestion, prevent and avoid congestion, and prompt notification of emergencies and emergencies on the transport and road network.