Speed characteristics of heterogeneous traffic on inter-urban roads in Indonesia

Abstract

Inter-urban roads in Indonesia accommodate heterogeneous traffic with mixed types of vehicles sharing the same lanes. The heterogeneity results in varied average speeds and speed deviations of different vehicle categories. Lack of posted speed limits, misplaced speed limit posts, and the vehicle speed and acceleration performances are among the possible factors leading to a wider spectrum of speed variations. Previous studies have been conducted to investigate speed characteristics, but few studies concentrate on the effects of heterogeneity. The present study analyzes the characteristics of traffic heterogeneity which is captured in six different types of vehicles, i.e. passenger cars, angkots, pickups, buses, trucks and motorcycles. Analysis was conducted on a set of six-year data of speed and speed deviations from 8 provinces. The average speeds and speed variations of different types of vehicles were analyzed for provinces with speed closeness created based on a Post hoc test. A pairwise multiple comparison was carried out to test the difference between each pair of means using R-E-G-W Q (Ryan-Einot-Gabriel-Welsch) Range test, which is a multiple stepdown procedure for One-Way Anova. Subset 1 consists of average speeds of NTT, NTB, South Sulawesi and Central Sulawesi. Subset 2 groups Central Sulawesi, South Sulawesi and South Kalimantan, subset 3 group consists of Bali and South East Sulawesi, and subset 4 groups South East Sulawesi and West Kalimantan. Within-group and between-group analyses were conducted on speeds and speed variations, and geographical comparisons by vehicle categories were made to a reference province. The results of this study can contribute to traffic policing, setting up the speed limits and traffic safety improvement programs.