Explorative spatial analysis of traffic accident statistics and road mortality among the provinces of Turkey
Introduction
Road traffic accidents are increasingly being recognized as a growing public health problem in developing countries. It is estimated that in the European Union 1.3 million traffic accidents occur every year, resulting in over 40,000 deaths (CEC, 2003). Turkey, a rapidly developing country, is a junction point between Asia and Europe in terms of its social and economic structure (Işıldar, 2006). The population is 70,586,256, and the number of drivers license holders is 18,877,354 according to the 2007 population census. There is an explosion in immigration and population, and a corresponding increase in vehicle numbers. Meanwhile gross domestic product and income per capita have grown rapidly in recent years. The increase in motor-vehicle ownership is very high in Turkey, 795,552 new vehicles being registered in 2007 alone. Although the population increased by 14.70%, motor-vehicle ownership increased by more than 75% between 1995 and 2007. During that period, the number of traffic accidents (167.98%) and injuries (30.45%) also increased. The number of deaths, however, decreased by 42.39%. The amount of material loss owing to traffic accidents was approximately $1.1 billion for 2007, excluding health expenses and loss of labor (TUIK, 2007).
Previous statistics have shown that casualty and fatality rates in Turkey are much higher than in developed countries with comparable vehicle ownership levels. Compared with other countries, Turkey's traffic death rates are deplorable. The rate of fatal accidents in Turkey is 20 per 100 billion vehicle-kilometers, whereas the rates in the UK, United States, and Germany are 0.9, 1.1, and 1.6 respectively. In the last decade, the rate of accident per 100 million vehicle-kilometers more than doubled (http://www.asirt.org/). Turkey, having fewer vehicles than other countries, is recognized as being unlucky in terms of fatal accident numbers.
Rapid expansion of road construction and increased numbers of vehicles means that road traffic accidents are becoming an increasingly serious public health problem in Turkey. Achieving reductions in the number of traffic accidents and deaths is a national priority. Despite the significant impact of traffic accidents and mortality on public health, the magnitude of the effects could be greatly reduced if preventative measures were taken in the safety-deficient provinces. The identification of safety-deficient regions on the highway network is aimed at comprehensive safety programs. Geographical information systems (GIS) are a very important and comprehensive management tool for traffic safety. GIS-aided spatial analysis provides information on hazardous regions, hot spots, warm spots, and so forth (Liang, Mo'soem, & Hua, 2005). The spatial component of traffic accidents has always interested researchers and GIS-users. Empirical examples of spatial analysis of traffic accidents are mainly concerned with black spot analysis in local areas (Erdogan et al., 2008, Levine et al., 1995, Loo, 2006, Thomas, 1996), with a few exceptions (Eksler, 2007, Hayakawa et al., 2000, La Torre et al., 2007, Lassarre and Thomas, 2005) regional data are often neglected. Regional variations in traffic accidents and mortality in Turkey have also received no attention so far.
This paper examines the regional disparities hidden behind national statistics on road accidents and fatalities in Turkey using GIS and spatial analyses. It is a common practice to compare cities or countries in terms of road safety performance and to rank them in terms of risk indicators such as the accident or death rates, which are often expressed as the number of accidents/deaths per 100,000 inhabitants (Lassarre & Thomas, 2005). In Turkey, regional differences in traffic accidents and traffic accident mortality and their underlying determinants have not been studied, although Turkey has large regional differences in socio-economic development. The study therefore describes preliminary investigations of road accidents and mortality in Turkey at the province level, adjusting for population and number of registered motor vehicles owing to socio-economical differences. The number of accidents and mortality ratio are modeled with variables through geographically weighted regression. Different types of software were used for visualization and spatial analyses of the accident data in the study (i.e., Arc GIS 9.2, developed by ESRI, GeoDa 0.9.5-I developed by Luc Anselin through the Center for Spatially Integrated Social Science at the University of Illinois (Anselin, 2004), CrimeStat 3.1 developed by Ned Levine, with support from the National Institute of Justice (Levine, 2006) and GWR 3.0 developed by Fotheringham, Brunsdon and Charlton (2002)).
Section snippets
Data, methods and analyses
Accident reports are prepared by police departments within the borders of municipalities and by the gendarmerie headquarters in the provinces without police responsibility. Spatial analyses were performed on the aggregated data reported by both police and gendarmerie in the provinces of Turkey from 2001 to 2006. Population by census year, annual intercensal rate of increase and mid-year population forecasts, number of traffic accidents, and records of road deaths (including deaths occurring
Results
In this study, exploratory spatial analyses and geographically weighted regression analyses were conducted for determination and understanding of the distribution of problematic provinces owing to accidents and accident-caused mortality.
The risk of becoming an accident victim is given as the number of such fatalities per population at risk. In its simplest form, risk for any province is determined by the raw-accident death rate divided by province population-number of registered motor vehicles.
Conclusions
Identification of safety-deficient provinces with GIS-aided spatial analysis will certainly help with the targeting of proper preventative measures. Application of GIS and spatial statistics gave information about the distribution of accidents and mortality at the province level in this study. GIS and spatial statistics facilitate analysis and decisions at the province level with regard to problematic areas and precautionary measures. Traffic accident analysis is a very complex topic owing to
Saffet Erdogan is an Assistant Professor at Afyon Kocatepe University in Turkey. He has a doctorate in Geomatic Engineering from Istanbul Technical University. His primary research expertise is spatial analysis and spatial statistical techniques and applications in different disciplines. He has been leading the Public Surveying discipline in the Surveying Engineering Division in Afyon Kocatepe University.
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Saffet Erdogan is an Assistant Professor at Afyon Kocatepe University in Turkey. He has a doctorate in Geomatic Engineering from Istanbul Technical University. His primary research expertise is spatial analysis and spatial statistical techniques and applications in different disciplines. He has been leading the Public Surveying discipline in the Surveying Engineering Division in Afyon Kocatepe University.