What Could Go Wrong? Lessons Learned from Trenchless Installations

Trenchless construction methods are used frequently for areas where open cut is not feasible, such as crossings of railroads, major roadways, and bodies of water. These installations often deal with difficult ground conditions and nearby or overlying infrastructure. Even when general guidelines for project planning and design are followed, such as performing geotechnical borings or including minimum equipment capabilities in project specifications, issues can still arise during construction. This paper will review several recent trenchless projects that have experienced construction issues, including obstructions and rock, unstable soils or sinkholes, and other installation issues. A general overview of the trenchless methods used, including microtunneling and pilot tube auger boring, and regional geology will be presented, along with potential risks and construction considerations of these methods. Lessons learned from these projects for consideration in future trenchless projects will be presented.