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Deceleration rate, time to collision and impact speed have been commonly employed as accident risk indicators. However, it is hard to assess the level of accident risk since these indicators have not been developed with measurable score criteria. This study focuses on the determination of measurable risk indicators which could be used to assess accident risk level and to determine more appropriate accident risk management strategies by using the descriptive qualitative approach. The data were collected from a braking maneuver test conducted on a dry and level closed circuit course. Risk was a function of accident probability and its possible consequences, while accident probability was determined based on the safety factor, i.e. the ratio of available stopping sight distance (ASSD) to minimum SSD (MSSD), which was used to determine the margin of safety. Subsequently, accident consequence was determined using the impact speed at a predicted point of collision along the braking distance path. The results show that accident risk could be easily determined using the proposed indicators, whilst an objective and appropriate accident risk management strategy could be determined based on the minimum margin of safety value which could be obtained from each risk exposure.

Abstract-Aggregate gradation is one important part of the performance of asphalt mixture. Workability is one of the important parameters in asphalt mixture design that can easily be done in the field. Marshall compactor type is the most widely used in Indonesia even in the world. Therefore it is necessary to measure the workability using a type of Marshall compactor. The purposes of this study were: (1) measures the workability of asphalt concrete on five aggregate gradation targets that would be obtained the relationship between gradation index (GI) and workability index (WI), and (2) Workability is one of the important parameters in asphalt mixture design that can easily be done in practice, not just a mixture must be strong and durable. The parameters workability with Workability Index (WI) at 8 types of mixtures Hot Rolled Asphalt (HRA) using a gyratory compactor [3]. The results showed that the mixture with a mixing temperature of 150 °C has the best workability (WI> 6) than on mixing temperature of 120 °C and 75 °C reduction in temperature caused by the transport process, placed and compacting. Reduction temperatures below 120 ° C will result in a mix of hard compacted so that it will have a low density, high air voids, and high permeability.The workability on a type of mixture of Asphalt Treated Base (ATB), Asphalt Concrete (AC), Hot Rolled Sheet (HRS) using Marshall compactor was evaluated [4]. Asphalt concrete aggregate grading is set at five types of gradation are gradation lower limit, between the lower and the middle, the middle limit, between the middle and the upper limit, and the upper limit. However, workability is measured only at middle limit optimum bitumen content, so it has not demonstrated the workability of the mixture for another aggregate gradation. How the test requires a relatively large specimen. Asphalt mixture is measured workability requires 6 specimens. If the duplo specimen, it takes 12 specimens only to find the one value of workability. Use of the different specimen of the mixture will be very prone to drift results because the position of the aggregate in the mix will be different with another specimen, the temperature will change, and the mixing process is done manually. The results showed the value of the workability of the asphalt concrete for five types of gradation does not have a significant influence. WI values of asphalt concrete are between 2.389 up to 2.396 [4].Workability of a large stone aggregate gradation, the maximum aggregate size is 37.5 mm was examined [5]. Three types of compactor, namely compactor press play or gyropac, kango hammer vibration compactor, and compactor with impact techniques of free fall (Marshall compactor). Workability is influenced by the level of asphalt and aggregate gradation. Asphalt content, the greater the content of asphalt gives a tendency easier for compacted or treated. Fuller aggregate gradation approach provides better workability. Further [5] make the relationship between the height of the test specimen with the number of gy...

Jalan yang memiliki kekasaran (roughness) permukaan yang buruk dapat menyebabkan ketidaknyamanan bagi pengguna jalan, kecelakaan lalu lintas, peningkatan beban dinamis pada permukaan jalan sehingga mempercepat proses kerusakan jalan, serta kerusakan kendaraan. Penelitian ini bertujuan untuk mengevaluasi kemantapan kondisi jalan berdasar nilai international roughness index (IRI). Evaluasi kondisi kemantapan jalan dilakukan pada 14 ruas jalan di Kota Yogyakarta, dengan perincian 4 ruas jalan arteri sekunder dan 10 ruas jalan kolektor sekunder. Data nilai kekasaran permukaan jalan (IRI) diperoleh dengan menggunakan alat NAASRA roughness meter yang mengacu pada SNI 03-3426-1994. Evaluasi kemantapan kondisi jalan dilakukan dengan membandingkan nilai IRI hasil survei dan batasan nilai IRI yang ditetapkan oleh Direktorat Jenderal Bina Marga. Hasil penelitian menunjukkan 14 ruas jalan yang dievauasi 64% dalam kondisi sedang dan 36% dalam kondisi baik. Dari ke-14 ruas jalan tersebut, ruas jalan Sisingamangaraja, Lowanu, dan Sugeng Jeroni memiliki nilai IRI tertinggi secara bururutan sehingga ketiga ruas jalan tersebut lebih diprioritaskan untuk mendapatkan penanganan