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Abstract

A median is required for a two-way road to separate traffic from opposing lanes and to prevent head-on collisions. However, studies indicate that medians are also perceived as hazards which need to be avoided during driving. This hazard perception is manifested in drivers’ changing behavior towards various types of medians along the driving lanes inform of their tendency to allow various safe distances to the medians. The Indonesian Highway Capacity Manual (IHCM) does not differentiate between types of medians and the influence on the drivers’ choice of safe margin to the medians. Therefore, this study looks into how the existence and types of medians influence the safety distances of different categories of vehicles from different types of medians as the manifestation of their perception of hazard potentials of medians. Traffic recordings on different categories of vehicles are used to obtain movement margins of vehicles along various medians during near-saturated traffic. Using the smallest values of 10 and 90 percentile of distances, the results show that drivers shy from 0.27 m to 0.82 m from medians. The result of this study will contribute to the change of applied assumptions used in determining the effective lane capacity to road safety-based assumptions.

Bahasa Abstract

Perilaku Pengemudi terhadap Jarak Aman Kendaraan-ke-Median berdasarkan Potensi Bahaya. Sebuah median merupakan persyaratan pada jalan dua arah untuk memisahkan arus dan mencegah tabrakan frontal. Akan tetapi, banyak studi menunjukkan bahwa median sering dipersepsikan sebagai potensi bahaya (hazard) yang perlu dihindari selama berkendara. Persepsi potensi bahaya ini mengakibatkan berubahnya perilaku pengemudi ketika berkendara sepanjang median yang berbeda yang termanifestasikan dalam kecenderungan memberikan jarak aman yang berbeda-beda terhadap median yang berbeda. Manual Kapasitas Jalan Indonesia (MKJI) tidak membedakan pengaruh akibat jenis median serta pengaruh jenis median terhadap pilihan jarak aman pengemudi terhadap median. Oleh karena itu, studi ini meneliti bagaimana keberadaan dan jenis median memengaruhi jarak aman kendaraan dengan kategori berbeda terhadap beberapa jenis median sebagai manifestasi persepsi potensi bahaya dari median. Penelitian ini menggunakan perekaman lalu lintas dengan beberapa kategori kendaraan dalam kondisi hampir jenuh untuk mendapatkan marjin gerakan kendaraan sepanjang jalan dengan median. Dengan menggunakan nilai terkecil 10 persentil dan 90 persentil jarak, hasil menunjukkan bahwa kendaraan bergerak 0,27 m hingga 0,82 m dari median sehingga berpotensi menurunkan lebar efektif lajur. Hasil dari studi ini dapat dijadikan dasar untuk melakukan perubahan terhadap penerapan asumsi yang digunakan dengan asumsi yang didasari keselamatan jalan dalam menentukan kapasitas efektif lajur.

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