Instrumentation and Monitoring of a Critical Aging Highway Culvert that is Approaching Failure

Highway culverts promote natural drainage, provide crossings of small-to-moderate width, and are critical structures within modern transportation networks. Culvert rehabilitations and/or replacements are inevitable as infrastructure ages, and owners are tasked with developing asset maintenance programs to ensure continued operation of transportation networks. Agencies may close a road while waiting for a culvert replacement or, as in this trial, may choose to monitor conditions and close the road if necessary. The subject of this study is the Lefurgey Brook Culvert located on NB11 near Campbellton NB; this structure consists of a corrugated steel plate arch culvert with 2.0 m width, 25.6 m length, and is buried beneath approximately 4.5 m of fill. This culvert is owned and operated by the NB Department of Transportation and Infrastructure (NBDTI), and the results of recent routine inspections revealed that the culvert is in very poor condition with observations including: severe deformation and reverse curvature along the pipe wall and invert, joint separations with water flowing behind the pipe wall, backfill visible at separated pipe joints, and corrosion of steel. The most severe conditions are observed at the inlet end, and erosion is present on the shoulder of NB11 near the inlet. Design of a replacement structure was initiated immediately and is scheduled for installation during summer 2023. For public safety and to provide continued operation of NB11 during the time leading up to replacement, an automated monitoring system was installed at the Lefurgey Brook Culvert. The monitoring system consists of a 25-m-long ShapeArray installed horizontally within the shoulder of NB11 near the inlet. The ShapeArray is connected to a Thread data acquisition system, which is configured for remote access using a cloud data hosting service. The purpose of this instrumentation system is to monitor vertical deformations above the culvert, and a “push notification” system is implemented to ensure that interested parties are notified immediately should excessive deformations be observed. Details of the instrumentation program and data collected during the first months of operation are described herein. If the trial is successful, NBDTI will implement this technology to monitor conditions at other failing culverts.