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Roadway departure (RwD) crashes are significant safety concerns, especially at horizontal curves. The design of these curves plays a crucial role in mitigating RwD crashes. Thus, a thorough understanding of the interaction between driver behavior, vehicle automation, and geometric design is vital. Substantive safety, which emphasizes the inherent safety in a road's design and function, serves as the foundation of our approach. Building on this, the study employs a safe system approach to investigate the performance of horizontal curves under both non-automated and partially automated conditions, using a reliability-based analysis focusing on Stopping Sight Distance as the primary driver demand. Factors including Perception-Brake Time and Take-Over Time for automated vehicles are examined. The analysis covers horizontal curves, characterized by their geometric design and crash data. Our findings highlight a shift in the performance of horizontal curves under automation, emphasizing the need to consider automation in roadway design within the safe system approach. This study demonstrates how a reliability-based analysis can guide designers in making informed decisions regarding the geometric design of horizontal curves to reduce RwD crashes. To enhance transportation safety in the era of increasing automation, ongoing exploration of the relationships between driver behavior, automation, and road design is indispensable.

Highway geometric design is a part of highway planning which focused on physical form planning, so it can fulfil the highway basic function. Highway geometric design consists of horizontal alignment and vertical alignment and each of them has its own calculation. Computer technology developments can produce softwares which is able to help and simplify the calculations of both alignments and the softwares also can produce designs which visualize the calciulation into 2D images. But 2D image is not real enough to imagine the realistic form of the highway. We need 3D visualisation to imagine the realistic highway. This paper explains how the system can produce the 3D visualisation from horizontal alignment and vertical alignment calculations. First, find the highway 3D position in the 3D coordinate. 3D coordinate has three component, x, y and z axis. From horizontal alignment calculation, we get the x and y value and from vertical alignment, we get the z value. After obtaining the 3D position, then the highway design can be drawn. This software can design the highway better because it can simulate the highway wether it is comfort enough to be passed. Abstract in Bahasa Indonesia : Desain geometrik jalan merupakan bagian dari perencanaan jalan yang dititik-beratkan pada perencanaan bentuk fisik sehingga dapat memenuhi fungsi dasar dari jalan. Desain geometrik jalan terdiri dari Alinyemen Horisontal dan Alinyemen Vertikal, dan masing-masingnya memiliki perhitungan tersendiri. Dengan adanya kemajuan teknologi komputer, mampu menghasilkan program komputer yang dapat membantu dan menyederhanakan perhitungan dari masing-masing alinyemen tersebut serta menghasilkan rancangan yang sesuai dengan kaidah yang berlaku, bahkan mampu membuat visualisasi dua dimensi dari rancangan tersebut. Namun visualisasi dua dimensi dirasa kurang mampu memberi gambaran secara nyata bentuk asli dari rancangan geometrik jalan. Oleh karena itu dalam penelitian yang dilakukan ini, dikembangkan suatu perangkat lunak yang menggunakan hasil perhitungan program komputer untuk alinyemennya dan elemen-elemen tambahan untuk menghasilkan visualisasi tiga dimensi yang sesuai desain. Pertama-tama dicari posisi jalan dalam ruang 3D. Dengan hasil perhitungan alinyemen horisontal akan didapatkan posisi mendatar dari sebuah jalan dan hasil perhitungan alinyemen vertikalnya digunakan untuk mendapatkan ketinggian jalan tersebut. Setelah mendapatkan posisi 3D barulah digambar. Hasil program visualisaasi ini dapat menampakkan posisi jalan dengan lebih baik sehingga bisa digunakan untuk mensimulasi apakah perancangan pembangunan jalan tersebut nantinya nyaman untuk dilewati, belokan atau tanjakan yang dirancang tidak berbahaya, dan lain sebagainya. Kata kunci: desain geometrik jalan, visualisasi tiga dimensi, alinyemen horisontal, alinyemen vertikal.