Managing Geotechnical Risks in Design–Build Projects (2018)

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1 Summary NCHRP 24-44 completed an extensive investigation into the issue of geotechnical risk in design- build (DB) projects. The Phase I and II research are complete and the results are contained in this report. The primary deliverable is a set of guidelines for managing geotechnical risk in DB projects. At this point, a number of questions regarding this topic have been answered. The major findings detailed in this report are summarized as follows:  The bulk of US construction case law demonstrates that owners are rarely successful in winning differing site conditions (DSC) claims.  Nevertheless, DOTs continue to rely on exculpatory language to try to shed geotechnical risk in DB projects.  The industry recognizes the risk shedding bias and perceives geotechnical risk to be much higher than the authors of DOT DB requests for proposal (RFP).  The result is the inclusion of contingencies for risks that may not be realized, which must logically increase the overall cost of the project.  The solution is to align the perceptions of geotechnical risk of the DOT and the DB team early in the process.  The study has identified progressive DB, DB with multiple notices to proceed, and DB with some fixed scope validation period as potential mechanisms to permit the early alignment of geotechnical risk perceptions. In other words, the surest way to quantify subsurface risk effectively is to start the digging and uncover the actual site conditions on which the project must be built. This can be accomplished through early contractor involvement and joint development of the geotechnical risk profile for the

2 DB project. That being said, this report details the research completed to find and or develop methodologies that permit the DOT and its industry partner to align their perception of geotechnical risks and perhaps their business objectives as well as early as practical during the delivery of a DB transportation project. The guidelines that accompany this final research report provide the following five strategies for aligning the DOT’s and its design-builder’s perception of geotechnical risk. 1. Implement early contractor design involvement through encouraging geotechnical ATCs during procurement. 2. Use DB process to address other subsurface issues involving third party stakeholders as early as practical in project development and delivery. 3. Raise the visibility of geotechnical issues in DB projects to ensure competing contractor teams understand the level of criticality on each project. 4. Avoid differing site conditions claims through enhanced contract mechanisms designed specifically for addressing geotechnical risks. 5. Promote an atmosphere of life cycle-based design and construction decision-making with respect to geotechnical risk on DB projects. The guidelines also furnish 25 geotechnical risk management tools that can be used to implement the above strategies on typical DB projects. Each tool was found to be proven as effective in the field.