Enhanced Culvert Inspections – Best Practices Guidebook

Culvert inspection is a key enabler that allows Minnesota Department of Transportation (MnDOT) to manage the state’s highway culvert system. When quantitative detail on culvert condition is required, an inspector will need to use enhanced inspection technologies. Enhanced inspection technologies such as; laser ring profiling, sonar, inclinometer, mandrel, hammer sound testing, core sampling, closed circuit television (CCTV), HIVE and JPEG mosaic testing, can measure or digitally record condition that would not be apparent from a simple visual inspection. In general, MnDOT should balance the higher cost of conducting an enhanced inspection against the quality of data needed. It is estimated that simple end-of-pipe visual inspection costs $0.07/ft. Enhanced inspections range from $0.23/ft to $6.50/ft with higher cost inspections providing more detailed data. Estimates are developed using year 2016 unit costs. Best practices for each type of inspection are identified and presented in this guidance document.  The full report is available online at http://dot.state.mn.us/research/reports/2017/201716.pdf