County engineers and MnDOT hydraulics engineers have to wear many hats. One of them is maintaining culverts — the channels beneath roadways that facilitate passage of water and wildlife.
But culvert maintenance is practically a field of knowledge unto itself. To help engineers identify and apply the best repair techniques for specific problems, MnDOT recently produced a best practices guide for culvert repair (links below).
“We wanted to develop a state-of-the practice and put it into one place so engineers could easily find the information they need,” said Lisa Sayler, MnDOT Assistant State Hydraulic Engineer.
It might not always be the most visible or exciting issue from the public’s perspective — although, as the video above illustrates, occasionally it can be very visible — but culvert repair is a critical issue for transportation professionals. In fact, MnDOT submitted the repair guidebook as one of its choices for the AASHTO-RAC’s 2014 high-value research publication.
“There are many different fixes and products available for failing or deteriorating pipes,” explained District 4 Hydraulics Engineer Jane Butzer, who requested the guidebook. “This guide steps through the different products and practices, and further assists the hydraulics engineer by providing special provisions and standard detail drawings to include in project plans.”
Culvert repair practices have evolved significantly in recent years, so it can be difficult for individual engineers to keep abreast of new practices that come from a wide variety of sources. The guidebook draws from a wide range of sources, including the Federal Highway Administration, the National Cooperative Highway Research Program, AASHTO and numerous state DOTs.
“We synthesized previous work and expanded it from there to provide more details and more quantitative guidance for some specific repairs. We tried to provide more specific design procedures than what we found in previous documents,” said project manager Bruce Wagener of CNA Consulting Engineers.
In addition to providing detailed explanations of rehabilitation and repair methods, the guide includes a table that compares most methods of repair.
Researchers will next conduct a brief feasibility study to identify which culvert repair methods can be observed and tested to document the cost, longevity and effectiveness of repairs.