Incorporating design consistency into risk-based geometric design of horizontal curves: a reliability-based optimization framework

Abstract

Reliability theory has recently been utilized to consider the uncertainty in highway geometric design and optimize highway cross-section design safety by reducing crash risk. However, despite the importance of design consistency among successive highway segments and its impact on safety, most previous studies optimized road segments individually. This approach could limit the applicability and transferability of the optimization frameworks in practice. Thus, a system reliability-based optimization framework is proposed in this study to design successive highway cross-section elements while achieving overall design consistency and safety. A sequential search procedure with the basin-hopping stochastic algorithm is adopted to optimize the successive horizontal curve segments. A case study of a 12 km segment with 94 horizontal curves in the Sea-to-Sky Highway, Canada, is considered. The results show that the proposed optimization framework provided higher consistency successive cross-section elements design while minimizing the number of expected crashes and providing consistent crash risk levels.