TDOT Maintenance crew’s cut and removed the deteriorated invert, and prepped the existing culvert for slip-line rehabilitation by pouring a concrete slab and laying channel iron for the InfraSteel liner to slide over. Once the concrete slab had cured, the InfraSteel liner sections were transported to the site in August 2020. An excavator was brought on site to move and position each liner section into place. TDOT utilized maitnenace and welding crews to join the liner sections together with full penetration welds, ensuring no possibility of joint failure. The liner was then pushed into the existing structure.
The liner section contained inverted bevels on the bottom of each seciton, allowing for welding to occur inside the liner. Welding of the top of the liner was accessible from the outside. A look inside the liner shows crossing bracing that is tac-welded into place ensuring each section keeps its shape during transportation. The cross bracing also serves as a “crosshair” when aligning the sections into place. These are left in place until the grouting process of the annular space is complete. (They can be removed if manipulation of the ends is required to ensure alignment of full penetration welds.)
Once the liner was pushed into place, TDOT proceeded to utilize pressurized grout to fill the annular space between the InfraSteel liner and existing structure. The end result is a new structure that will continue to serve the Volunteer State for another 70+ years. More than just a component of the highway infrastructure, culverts or groups of culverts, serve an important purpose to carry drainage water from one side of a roadway to another; in addition, they also serve a bridge function to transport the traveling public across waterways. They can be found with round, boxed, elliptical, or arched construction. The overall condition of the approximate 4 million miles of culverts across the country varies, but many have been in service for 30-70 years and are reaching the end of their designed service life.
This need has led to the growing market of trenchless rehabilitation. It is now possible to fully rehabilitate or repair a structure with no impact to the roadway or traveling public. According to a recent article by Trenchless Technology, “State and local governments have become more aware of and are utilizing trenchless rehab methods for repairing their aging and deteriorated culvert and drainage systems…currently, the rehabilitation of storm water pipelines and culverts is estimated to be 15 to 20 percent of the overall trenchless rehabilitation marketplace.”
States and counties with active culvert inspection programs are less likely to experience a catastrophic failure or roadway collapse.
It is as equally important for all infrastructure professionals and traveling public to be aware, and on the lookout, for the common signs of an impending culvert failure. Many potential failures can be identified from the roadway surface by paying attention to the tell-tale signs of pavement cracking, eroding embankments, and dips or drops in the road and guardrails where there are creeks or streams.