Investigating the effect of asphalt surface friction coefficient on accidents (case study of Isfahan city)

Dissertation of the master's degree in the field of accidents

Abstract:

Safety in vehicle traffic is one of the most basic foundations in traffic engineering and transportation planning in the world. Non-observance of safety principles in the design of roads, maintenance and planning of transportation and traffic in the country has caused heavy damages to the society.

Skid resistance [1] is one of the important parameters for determining the condition of the asphalt pavement and finally it is an important factor for road safety, which plays an effective role in preventing accidents caused by slipping. Research shows that skid resistance has an impact on accidents. As a characteristic of the pavement surface, this parameter is affected by two types of fine and coarse texture of the surface, which are measured by different means and methods. Among these methods, the English pendulum method is considered a suitable evaluation method of road surface slip resistance. In this research, we are trying to find out

Is the friction coefficient of the asphalt surface related to the rate and occurrence of accidents?

Is the type of stone material considered an important and effective factor in determining the friction coefficient of the asphalt surface?

Asphalt prepared from limestone (one of Isfahan quarries) and silica and quartz (one of Tehran quarries) materials was measured and then compared with each other. Finally, the normalized relative accident statistics in Isfahan city and 21st district of Tehran municipality were obtained (the complete accident forms of Isfahan city and 21st district of Tehran municipality in 2018). The order of the effect of friction coefficient on accidents will be determined; Therefore, the following results, which were among the objectives of the research, are obtained from this research.  

1 Obtaining an index to measure the friction coefficient of the asphalt surface

2 Investigating the role of the friction coefficient on the amount of accidents in Isfahan city

3 Investigating the role of the type of stone materials on the friction coefficient of the asphalt surface

Key words: friction coefficient, urban roads, asphalt, accidents

Chapter 1

Research overview

11 Introduction:

"And I revive people, so I revive people in general"

Whoever gives life to a soul (saves it from death) is like giving life to all people

    (Holy Qur'an: Surah Ma'idah verse 32)

Human beings from the very first days of the emergence of civilization in pursuit of the development and improvement of communication channels It was in such a way that every land that was a pioneer in this field was more prosperous and successful, and in fact, the secret to the success and durability of a land and civilization lay in having better means of transportation and communication. Therefore, the rulers paid special attention to the improvement of vehicles and the development of communication routes, which was sometimes for the purpose of facilitating the transportation of people and equipment for the purpose of opening up the country and expanding the territory under their rule, and not necessarily for the well-being of the people of the land under their rule. In any case, for various reasons, human enthusiasm and enthusiasm for the rapid transportation of goods and people caused the rapid growth and improvement of vehicles and the development of communication routes, among which roads and ground vehicles for the reasons of accessibility, cheapness and so on. received more attention. With the invention of the steam engine, a revolution was created in the field of improving ground transportation vehicles, and vehicles were produced with more speed and power every day. On the other hand, along with the progress of the media and the development of roads, traffic problems, and accidents at the head of them, became a problem for people and gradually became a social problem that drew the attention of governments to the category of traffic safety. Accidents are one of the biggest public health problems in the world (Ivans, 2004). Traffic accidents are a huge disaster for the society, to the extent that it destroys 2-3% of the national wealth in our country (Iraj Laighi, 2014). The World Health Organization has found that every year 3% of the per capita income of countries that are saving money is spent on financial losses caused by traffic and traffic accidents (Iraj Laighi, 2015). Traffic safety can reduce the level of human vulnerability in the use of the transportation industry. Give it as needed.Controlling the speed of cars, increasing the road safety factor, mandating car safety points and raising the level of people's traffic culture.

Complying with standards and using high-quality materials in road infrastructure and paving are among the measures that can be effective in road safety. In the meantime, choosing the right asphalt that meets the standard conditions, including proper abrasion resistance. has a significant role in road safety; Therefore, according to the role of the friction coefficient in the occurrence, non-occurrence, increase or decrease of the severity of accidents, the selection of primary materials that provide the appropriate friction coefficient on the asphalt surface can be effective in reducing or reducing the severity of accidents. In this research, we seek to compare the accidents of two cities that have used different materials in the production of asphalt for their roads, to investigate the importance of using better materials in reducing or reducing the severity of accidents, and to determine its extent, so that the traffic safety supervisors become more sensitive to this issue, and we also contribute to traffic safety and, as a result, prevent the bloodshed of people in accidents.

12 Plans Problem:

So far, there have been several researches about the effect of the friction coefficient of the surface of urban roads on accidents; But this issue has been paid less attention in the city of Isfahan. The special characteristics of the asphalt surfaces of the roads of Isfahan city and the traffic culture of its drivers highlight the necessity of this research about the city of Isfahan. It should be noted that the stone materials used in asphalt mixtures in Isfahan city are of limestone type, and thus the abrasion resistance of asphalt surfaces decreases drastically. This problem affects the friction coefficient of the road surface. It is obvious that the lower the friction coefficient of the asphalt surface with the car tire, the higher the probability of an accident. Thus, in this research, an effort will be made to obtain the relationship between the friction coefficient of the asphalt surface and the rate of accidents in Isfahan city, and to explain the role of the type of stone materials in the rate of accidents. This issue will be investigated by comparing the normalized accidents situation in Isfahan city and district 21 of Tehran municipality (which has asphalt mixtures of siliceous-quartz stone materials). According to the results of this research, the following questions will be answered:

Is the coefficient of friction of the asphalt surface related to the rate and occurrence of accidents?

Is the type of stone material considered an important and effective factor in determining the coefficient of friction of the asphalt surface?

Is the coefficient of friction of the surface of urban roads with car tires an estimable parameter?

1-3- Importance and necessity of research:

Safety in vehicle traffic is one of the most fundamental bases in traffic engineering and transportation planning in the world. Non-observance of safety principles in the design of roads, maintenance and planning of transportation and traffic in the country has caused heavy damages to the society. Slip resistance[1] is considered as one of the important parameters for determining the condition of the asphalt surface, and finally, it is an important factor for road safety, which plays an effective role in preventing accidents caused by slippage. Research shows that skid resistance and road width have an impact on accidents. This parameter, as a feature of the pavement surface, is affected by two types of fine and coarse texture of the surface, which are measured by different means and methods. Among these methods, the English pendulum method [2] is considered a suitable evaluation method of road surface slip resistance. In 1939 to 1945, due to the increase in motor vehicles and heavy traffic, the need to study sliding resistance was found. On the other hand, it is important to choose the type of stone materials for the preparation of asphalt mixture. One of the parameters for choosing the type of stone materials is the polishing value of stone materials [3]. Stone materials are divided into three general groups in terms of polishing value. Materials with low polishing value include carbonate stones, materials with medium polishing value include igneous rocks, and materials with relatively high polishing value include sandstones; Therefore, choosing the right type of stone materials can reduce the polishing of roads and ultimately increase traffic safety. The necessity of this is clear for an important and extensive province such as Isfahan, the transit crossroads of the country. 14 research hypotheses: In pioneer countries in the field of road safety in order to reduce accidents, the selection of high-quality materials in order to optimize the infrastructure and pavement is at the top of the measures. The very low statistics of the number of accidents in these countries indicate the high impact of road safety in reducing accidents.