Contractual Approaches to Address Geotechnical Uncertainty in Design-Build Public Transportation Projects

Geotechnical uncertainty may be the most difficult risk to manage in construction. In design-build (DB), where the project’s price is fixed before design and in many cases the subsurface investigation is complete, the risk profile is fundamentally changed and the owner must address it. This paper assesses the potential of DB as a tool for addressing geotechnical uncertainty in public transportation projects by comparatively evaluating three successful approaches. The first case study involves the use of a geotechnical baseline report as a subsurface condition risk allocation tool. The second uses unit price pay items inside the larger lump sum contract to share the geotechnical risk with the design-builder. Finally, a “nested DB” landslide repair clause inside a design-bid-build interstate highway contract successfully addressed the post-award potential landslide risk. The paper concludes that each of the contractual management approaches provided an effective means for addressing geotechnical uncertainty in DB public transportation projects