Istrazivanja i projektovanja za privreduJournal of Applied Engineering Science


DOI: 10.5937/jaes0-25837 
This is an open access article distributed under the CC BY 4.0
Creative Commons License

Martha Leni Siregar
Universitas Indonesia, Faculty of Engineering, Department of Civil and Environmental Engineering, West Java, Indonesia

Tri Tjahjono*
Universitas Indonesia, Faculty of Engineering, Department of Civil and Environmental Engineering, West Java, Indonesia

Universitas Indonesia, Faculty of Engineering, Department of Civil and Environmental Engineering, West Java, Indonesia

Speed performances and characteristics of traffic have mostly been considered as homogeneous across vehicles. In countries where the roads are dominated by mixed types of vehicles, the heterogeneity needs to be considered. This study is aimed at modeling how traffic heterogeneity as captured in speed, speed deviation, and traffic volume determines the fatality rates and accident rates. Traffic volume, road geometry (bendiness, hilliness, bend density and hill density) and road surface condition (represented by IRI) become the independent variables in a simultaneous regression using structural equation model (SEM). SEM is adopted to represent the hierarchical causal effects between the independent variables and dependent variables. The data cover inter-urban roads in eight provinces in Indonesia from 2012-2016 and 2019. Speed is not significant in predicting accident rate, and speed deviation is not significant in predicting fatality rate. An increase in speed deviation lowers the accident rates; an increase in speed increases fatality rates. Road geometry and traffic volume negatively impact the speed deviations of all vehicle categories, indicating that when there is more traffic on the road, the speeds of all vehicle categories become more homogenous. Bend density, bendiness, hill density and hilliness negatively affect both the speed and the speed deviations of the vehicles of all categories The findings of the study can contribute to traffic policing and traffic safety improvement schemes for heterogeneous traffic.

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This research was funded by UI PUTI Doktor Grant 2020, contract number NKB-663/UN2.RST/HKP.05.00/2020. The Authors would also like to thank the Project Management Unit of the Australian-funded “EINRIP MONITORING & EVALUATION PROGRAMME, Fifth Monitoring Survey, Final Report 2017” for the permission to use the data.

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