IMPACT OF PAVEMENT AND GEOMETRIC PARAMETERS ON ROAD SAFETY

Abstract

Road transportation is more favored as it is cheaper and faster than other modes. However, a higher probability of getting involved in crashes reveals its negative impact. The frequency of road traffic fatalities has escalated pointedly in the past decade. Around 1.35 million people globally lose their lives yearly in these road accidents. Almost all countries around the world are experiencing this inevitable phenomenon, rather than one country. However, developing countries witness a higher number of crashes (about 93%) and crash related deaths despite these countries having approximately 60% of the world's vehicles. As a result, road traffic accidents are a major socio-economic problem in developing countries rather than developed countries. Similarly, India, a developing nation in south Asia, observed more than 0.15 million deaths in 2019 due to Road Traffic Accidents (RTAs). As a result, the social and economic price of these crashes in 2019 was about $ 38.81 billion, roughly about 1.35% of India's Gross Domestic Product (GDP). According to (MORTH, 2019) the Ministry of Road Transportation and Highways, these fatalities are about 13% of total fatalities all over the world. Further, statistics show that rural roads (only National and State highways) observed 54.9% of total crashes despite these roads constituting only 5.04% of the total road network. Road accidents are random, as these are influenced by a range of factors. However, these factors are not limited to driver's behaviour or distraction but are also influenced by other external factors such as roadway characteristics (geometric design and pavement surface quality) and vehicle characteristics. Past research shows that inconsistent pavement and geometric design reliably affect ride quality and ultimately subsidize drivers' disruption. However, it is less clear how and to what extent exactly pavement and geometric conditions are related to road crashes. Thus, to contribute to this growing body of knowledge, the study tried to find out the impact of pavement and geometric parameters on rural road crash rate in the context of emergent nations, where crash-related data is rarely available and heterogeneous traffic conditions exist. Though some studies were conducted in this context but are insufficient for developing suitable policies and strategies. Differentiating with past studies, this study tried to identify the impact of pavement surface irregularities on crash frequencies in addition to geometric design variables. In summarized form, this study has made several significant contributions. Firstly, this study conducted a systematic literature survey to provide an overall perspective of significant findings of past research work related to RTAs. The literature provides information about the hierarchy of risk variables, methodological approaches of past studies and the possible types of statistical tools that can be used in safety research. Secondly, this study aims to develop Accident Prediction Models (APMs) that allow respective authorities to identify contributing variables that may significantly impact crashes occurring on rural roads and highways in India. Thus, collision and severity based APMs were developed to achieve the objective as a function of road geometry, pavement surface condition, and traffic parameters. Thirdly, it suggests best practices and approaches to address traffic safety problems with reliance on limited data by comparing the goodness of fit of the developed models. Lastly, it provides conclusions from comparable studies in developed nations, which may not be directly applicable to developing nations due to significant variations in traffic flow, roadway design and roadside features and, most crucially, behavioural factors. Thus, the results of this study shed light on different types of crashes based on the type of location, type of collision, type of severity and type of vehicles involved that occurred on rural roadways in developing nations and generally in India. Thus, it intends to provide a tool for highway engineers to validate their decisions while selecting the best-performing model, as the study highlights significant issues with road safety in emerging nations.