4 Details of Field Testing of Major Trenchless Technology Methods for Road Crossings

Ground displacements and borehole stability are always of prime concern during trenchless technology installations under pavements, and in close proximity to existing buried utilities and structures. Stable boreholes also relate to successful completion of the projects. The Missouri Department of Transportation (MoDOT), University of Missouri — Columbia, Michigan State University, and several industry participants have joined forces to conduct a research program to evaluate borehole stability. The objective of this research is to study the ground movements caused by pipe jacking, pipe ramming, guided boring (also known as pilot tube microtunneling), and horizontal directional drilling methods. The soil displacement in the vicinity of the cutterhead, reamer and at the ground surface will be examined. To conduct the research, several field installations were conducted at the University of Missouri's Capsule Pipeline Research Center during the summer of 2002. In addition, an actual road crossing with pipe jacking method was closely monitored. The results of these unique field evaluations were incorporated in the MoDOT specifications and guidelines and a summary will be presented in this paper. The results of this research show that, when properly used, trenchless construction methods can be cost saving options capable of installing utility and pipelines under roads and highways with minimum soil and ground movements.