DEVELOPMENT OF A CRASH FREQUENCY MODEL OF INDONESIAN FREEWAYS

It is imperative to comprehend the factors that contribute to traffic crashes if they are to be reduced effectively. This study aimed to develop a crash frequency model of Indonesian inter-urban freeways. Data was collected from four inter-urban freeway toll roads. The freeway toll-road operators provide traffic volumes, geometric characteristics, and crash data. To develop the crash frequency model, the author performed a negative binomial regression analysis. The predictors included certain highway geometric factors and the hourly traffic volume. The results show that the frequency of crashes was significantly associated with the volume of traffic per hour and geometric factors. Specifically, section length, hourly traffic volume, and the width of the roadway and outer shoulder positively impacted crash frequency, while horizontal curve and inner shoulder width had a negative impact. Moreover, road divider (median) type and time of day had significant impacts on inter-urban freeway crash occurrences. The results have important implications, as they reveal the relationship between freeway design parameters and traffic crash frequency. This knowledge will aid the development of new design methods that consider safety explicitly.