Climate-resilient infrastructure: lessons from the 2024 flood-induced failures of Nepal’s BP highway

The September 2024 floods along Nepal’s Banepa–Bardibas Road, commonly known as BP Highway, resulted in one of the most severe transport infrastructure failures in the Himalayan region to date. These floods, triggered by an extreme three-day rainfall event (including a 24-hour deluge exceeding 300 mm at multiple stations), heavily damaged the 26 km stretch between Bhakundebesi and Nepalthok. Using chainage-level field reconnaissance, rainfall analysis, and a review of emergency response and rehabilitation measures, this study provides the first integrated documentation of the hazard cascade, infrastructure failures, and institutional responses along the severely impacted road section. The results reveal distinct failure modes, including complete washouts, retaining wall and toe protection collapses, and debris-induced blockages, driven by interacting flood processes (riverbank erosion and sediment surges). Despite early national flood alerts, preparedness remained reactive, causing severe bottlenecks; recovery efforts relied heavily on emergency diversions and temporary gravel tracks. International comparisons show that, while global authorities now embed climate risk into design standards, Nepal’s roadway network remains anchored in obsolete design return periods. This study provides the first integrated, chainage-level documentation of the hazard cascade, infrastructure failure typologies, and institutional response along a severely impacted Himalayan river-corridor roadway, combining field reconnaissance, rainfall analysis, and international benchmarking within a single corridor-scale analytical framework. The findings demonstrate that compound hazard interactions, particularly the amplification of flood impacts by quarry-induced channel constriction and systemic gaps in risk-informed planning are the defining drivers of infrastructure vulnerability in this and comparable mountain road corridors across South Asia.