Spatial Analysis of Accident Spots Using Weighted Severity Index (WSI) and Density-Based Clustering Algorithm

Abstract

This study is based on evaluation of various factors that cause road accidents in Lagos Metropolis. Fourteen (14) factors/drivers were identified which tend to influence an occurrence of accident on Lagos roads. In order to study the pattern of accidents in the Metropolis, several different spatial and non-spatial datasets were collected, processed and analysed. Weighted Severity Index (WSI) was created based on these factors/drivers. Also, Density-based Clustering for Traffic Accident Risk (DBCTAR) was carried out to assist in ascertaining the distribution of Black Spots Severity (BSS). Results obtained include: shortest-path analysis, service area analysis, accident spot severity and vulnerability level across the Metropolis based on the Weighted Severity Index (WSI). The study reveals that, accidents are not always caused as a result of bad roads but by the smoothness of roads such as expressway with accident spots distance band of 300m-500m and 3.6% of the accidents is as a result of pedestrians avoiding the use of pedestrian bridges/aid even when they are available. © JASEM https://dx.doi.org/10.4314/jasem.v21i2.22 A road accident refers to any accident involving at least one road vehicle, occurring on a road open to public circulation, and in which at least one person is injured or killed (National Institute of Statistics and Economic Studies, saved 2017). Road traffic injuries are a major cause of morbidity and mortality worldwide, but especially in low-and-middle income countries (Nkwonta, 2013). The World Health Organization (WHO) estimates that more than 3000 people are killed every day in road traffic crashes globally, with at least 30,000 others injured or disabled. This adds up to over 1 million people killed and between 20-50 million injured or crippled in road traffic crashes each year (WHO, 2013; Krug, Sharma and Lozano, 2000). Unfortunately, the popular means of transportation in Nigeria is the road transport. Road accidents do not simply happen, they are caused (Sheriff, 2009). The causes of road traffic accidents are multi-factorial. These factors can be divided broadly into three (3) major factors, they literally include: Driver, Vehicle and Roadway factors. According to Eze (2013), accidents can be caused by a combination of these factors. He analysed that driver factors solely contribute to about 57% of road traffic accidents and 43% either alone or in combination with other factors. Details on these factors can be found in Agbonkhese et al. (2013); Abiola (2011 and Atubi (2010).