An investigation of reasons and consequences of deteriorated hydraulic capacities of culverts concerning railway track stability

The establishment of railway routes requires earthworks and the construction of tunnels, culverts, bridges, and viaducts. Railway routes can pass through highly variable regions in terms of geography, climate, hydrology, and land use, which require careful consideration of the possible effects of each aspect on the safety and serviceability of the railway service along a route. Culverts are very important civil engineering structures designed to allow passage across the railway route. Culverts are part of the railway substructure and most culverts are designed for hydraulic purposes. Hydraulic culverts can allow the passage of small streams and surface flows that arise after heavy rains and floods across the railway route. They must provide a sufficient cross-sectional area for the passage of current and future estimates of flow rates expected to occur across the railway route. The flow rate that the culvert can accommodate is the hydraulic capacity culvert, which is determined by the unobstructed cross-sectional area of a culvert. The hydraulic capacity of a culvert can deteriorate by sedimentation and can become insufficient due to climate changes that are unaccounted for and changing land use patterns. Therefore, the railway authority must monitor the states and functionalities of its culverts along its railway network and update their service lives with the ongoing changes that occur along the railway route that can influence the service lives of the culverts. This study elaborates on the conditions that can reduce the functionality of culverts and provides two case studies where reduced culvert functionality has resulted in the collapse of railway track structures and consequential train derailments.