Introduction

The underground construction industry in North America has made significant advances in developing and implementing methods to avoid and resolve disputes during construction. These evolved in the wake of years of disruptive and antagonistic project disputes and ensuing time consuming and costly litigation. Projects involving subsurface excavation present many risks, all of which must be allocated to either the owner or the contractor during design development. The greatest risks are associated with the subsurface materials encountered and their behavior during excavation and installation of ground support. The main purpose of the general baseline report (GBR) is to clearly define and allocate these risks between the contracting parties. The principal purpose of the GBR is to set realistic, measurable, and observable baselines that represent the best estimate of subsurface conditions that will be encountered during construction.