Explorative spatial analysis of traffic accident statistics and road mortality among the provinces of Turkey

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Abstract

Introduction

The aim of the study is to describe the inter-province differences in traffic accidents and mortality on roads of Turkey.

Method

Two different risk indicators were used to evaluate the road safety performance of the provinces in Turkey. These indicators are the ratios between the number of persons killed in road traffic accidents (1) and the number of accidents (2) (nominators) and their exposure to traffic risk (denominator). Population and the number of registered motor vehicles in the provinces were used as denominators individually. Spatial analyses were performed to the mean annual rate of deaths and to the number of fatal accidents that were calculated for the period of 2001–2006. Empirical Bayes smoothing was used to remove background noise from the raw death and accident rates because of the sparsely populated provinces and small number of accident and death rates of provinces. Global and local spatial autocorrelation analyses were performed to show whether the provinces with high rates of deaths–accidents show clustering or are located closer by chance. The spatial distribution of provinces with high rates of deaths and accidents was nonrandom and detected as clustered with significance of P < 0.05 with spatial autocorrelation analyses.

Results

Regions with high concentration of fatal accidents and deaths were located in the provinces that contain the roads connecting the Istanbul, Ankara, and Antalya provinces. Accident and death rates were also modeled with some independent variables such as number of motor vehicles, length of roads, and so forth using geographically weighted regression analysis with forward step-wise elimination. The level of statistical significance was taken as P < 0.05. Large differences were found between the rates of deaths and accidents according to denominators in the provinces. The geographically weighted regression analyses did significantly better predictions for both accident rates and death rates than did ordinary least regressions, as indicated by adjusted R2 values. Geographically weighted regression provided values of 0.89–0.99 adjusted R2 for death and accident rates, compared with 0.88–0.95, respectively, by ordinary least regressions.

Impact on industry

Geographically weighted regression has the potential to reveal local patterns in the spatial distribution of rates, which would be ignored by the ordinary least regression approach. The application of spatial analysis and modeling of accident statistics and death rates at provincial level in Turkey will help to identification of provinces with outstandingly high accident and death rates. This could help more efficient road safety management in 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.

References (29)

  • T. Traynor

    Regional economic conditions and crash fatality rates — A cross-county analysis

    Journal of Safety Research

    (2008)
  • L. Anselin

    Local indicators of spatial association—LISA

    Geographical Analysis

    (1995)
  • L. Anselin

    GeoDa 0.95i release notes

    (2004)
  • L. Anselin et al.

    Spatial analyses of crime

    Measurement and Analysis of Crime and Justice

    (2000)
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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.

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