Tunnel Business Magazine

OCT 2018

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Page 22 of 47

TUNNELINGONLINE.COM TBM: TUNNEL BUSINESS MAGAZINE // OCTOBER 2018 in design development. Is or should that be a purpose of a GBR in DB? If the objective of including statements as to design as- sumptions or approaches is to define a ba- sis for potential risk transfer to the owner, does that objective, given the DII Factors, undermine and subvert other Contract Document provisions exclusively (or even primarily) assigning design responsibility to the design-builder? Perceived Subversion of Risk Transfer Objectives in DB Some DB owners may perceive that any (and especially any significant) risk sharing for subsurface conditions may subvert or undermine Contract Docu- ment provisions assigning exclusive re- sponsibility for design adequacy to the design-builder; and that given the DII Factors, it would neither be realistic nor manageable to share subsurface condi- tions risk without accounting for the im- pact and influence of the design-builder's design adequacy risk on the triggers for subsurface conditions risk allocation. Owners having this perspective are concerned that – given the DII Factors – by sharing subsurface conditions risk they may – by extension – assume adjunct and interdependent risk for design adequacy if the design-builder's final design approach proves to be incompatible, unsuitable or unconstructable given the actually en- countered subsurface conditions. A related concern of those owners is that by contractually assuming some de- gree of risk for certain aspects of design ad- equacy (for example, for owner-furnished prescriptive design) they may directly or impliedly assume warranty or other responsibility for the compatibility, suit- ability and constructability of that design in the anticipated or actually encountered subsurface conditions. The latter concern is intensified in circumstances in which the owner has specifically disclaimed the accuracy, suitability and completeness of owner-furnished subsurface data or eval- uations and has not agreed to share risk if the actual conditions are materially differ- ent from those anticipated. Should these concerns be realized, the owner would be exposed to subsurface conditions and/or design adequacy risks that otherwise, by contract, are exclusive- ly assigned to the design-builder. These concerns are valid, and emphasize the proximate connection and interface be- tween subsurface conditions and design adequacy risks, and the need for clarity and coordination in the concerted defini- tion of risk allocation boundaries in both of those respects. Differing Subsurface Conditions Encoun- tered During Design Development On major DBB and DB subsurface proj- ects, DSC claims are typically identified and asserted during construction. How- ever, in DB, depending upon the particular contractual approach to subsurface condi- tions risk allocation, a design-builder may identify and assert a DSC claim during the design process when the design-builder's (a) subsurface investigation, testing, stud- ies, or evaluations, and/or (b) design devel- opment, demonstrate that (i) subsurface conditions are materially different than reasonably expected (or objectively stated in the GBR) and (ii) those differing condi- tions require an approach to final design substantially different from that required by the owner's mandated criteria or stan- dards and/or the basis of the design-build- er's tender design approach. The GBR Purpose is Risk Allocation, Not Design Basis Definition or Development In some DB projects, disputes have arisen between and among owners and design-builders (and their respective consulting engineers), as to the follow- ing issues: • Given the primary and Contract Doc- ument status of the GBR – considered relative to the diminished (e.g., lower priority) and frequently disclaimed and "no reliance" (e.g. reference in- formation document) status of data, or other reports, such as the GDR – is the design-builder (and its consulting engineer) entitled to rely (exclusively or primarily) upon statements, charac- terizations, and descriptions of subsur- face conditions in the GBR as a basis for design development? Alternative- ly, must or should that design develop- ment be based upon actual data (i.e., the product of subsurface investiga- tion and testing) and not primarily or exclusively upon GBR "interpretive" or baseline statements? Put another way, is the GBR purpose limited to risk allocation, or is the GBR intended to provide a basis for reliance in the de- velopment of an adequate and suitable final design consistent and compatible with reasonably anticipated subsur- face conditions? • Is an owner entitled to mandate that (or otherwise constrain the profes- sional judgment of) the design-build- er (and its consulting engineers of record) accept and utilize, for exam- ple, ground classifications or charac- terizations articulated in the GBR, as the basis for design development and finalization? These issues and the underlying inter- faces – viewed discreetly and collectively – demonstrate and reinforce the con- nections and interdependencies (i.e., the DII Factors) between subsurface condi- tions and design adequacy risks, and the complexities and challenges involved in achieving effective and balanced risk al- location in DB subsurface projects. Integrated Risk Allocation Baselines Approach A less insular, fragmented and more universal and integrated approach to risk allocation for both subsurface conditions and design adequacy should be adopted. The preceding discussion supports the following observations and recommended approach: • In major DB subsurface projects, the Contract Documents should include composite and integrated baseline statements ("Integrated Risk Al- location Baselines" or "IRAB") that objectively define and articulate the allocation of risks as between the owner and design-builder for both subsurface conditions and the an- ticipated final design approach basis for permanent work ("permanent design basis"). • The IRAB approach is predicated upon the precedent and prudent owner decisions to (1) perform ex- ploration and testing of subsurface conditions pre-tender sufficient to provide a reasonable basis for the design-builder's reliance and use in the development of preliminary de- sign compatible with the anticipated subsurface conditions; and (2) share subsurface conditions risk with the design-builder. • The IRAB should evidence and con- firm, as an integral part of the Con- tract Documents, the mutual risk allocation understandings and agree- ments of the owner and design-build- er pertaining to the DII Factors that are relevant to the alignment and interaction of subsurface conditions and design adequacy risks. • In DB projects the IRAB should be incorporated into the GBR. The discussion of the permanent de- sign basis in the IRAB provisions of the GBR should be consistent with other portions of the Contract Doc- uments that pertain to the perma- nent design basis. • Alternatively, the discussion of the permanent design basis portion of the IRAB may be incorporated into a separate design basis report ("DBR") 2 3 F E AT U R E S T O R Y

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