"Culvert rehabilitation remains a growing industry in an aging infrastructure. Vermont Agency of Transportation (VTrans) has, for a couple of decades, taken the lead on identifying, inspecting and addressing culverts for potential rehabilitation that are near the end of their useful life.
VTrans has used various methods including open cut and replacement, reinforced concrete inverts and segmental sliplining. A majority of the rehabilitated culverts under Vermont’s interstate and state road system are relined with a new smaller pipe with the same roughness coefficient as many culverts built in the 1950s and 1960s were, fortunately, oversized based upon older hydraulic analysis tools.
Open-cut and replacement is expensive, especially under deep fills, and VTrans has only completed those where the hydraulic capacity cannot be accommodated. In many cases that approach can be three to five times more costly when factoring in staged construction and maintenance of traffic."
"Interstate Culvert Rehabilitation in Vermont During Early COVID-19 Shutdown" | February 16, 2021: https://trenchlesstechnology.com/interstate-culvert-rehabilitation-in-vermont-during-early-covid-19-shutdown/