FIDIC黄皮书下的变更：Uniform Building Contractors Ltd诉特立尼达和多巴哥供水和污水管理局的经验教训

Lessons fromUniform Building Contractors Ltd v. The Water and SewerageAuthority of Trinidad and Tobago July 2026 A recurring tension under lump-sum EPC and design-buildcontracts is the distinction between a genuine “variation”and work that simply falls within the contractor’s originalcontractual obligations. Indeed, according to the EighthAnnual HKA Crux Insight Report, from a pool of 2,204engineering and construction projects in 114 countries, 34.7%of all claims or disputes arose because of “changes in scope”. 3.Procedural compliance– The contractor must providetimely notice under Clause 20.1 and follow all mandatoryvaluation mechanisms. The Privy Council reaffirmed thatClause 20.1 of the 1999 FIDIC Yellow Book, as written,operates as a condition precedent under English law.The Privy Council did not address the procedures forsubmitting a detailed claim. However, under the 1999FIDIC Yellow Book, noncompliance with those proceduresmay adversely affect its assessment – including thepotential reduction or rejection of elements of the claimto the extent that such noncompliance has prejudiced theengineer’s or employer’s ability to evaluate it properly. The recent Privy Council decision inUniform BuildingContractors Ltd v. The Water and Sewerage Authorityof Trinidad and Tobagoprovides helpful guidance on howcourts and tribunals may approach that question. While thecase concerned the 1999 FIDIC Yellow Book, the underlyingrisk allocation and contractual structure are substantiallysimilar to the 2017 edition. 4.Substantiation– The claimed costs must be properlyvalued and substantiated in accordance with thecontractual valuation mechanism. The contractual test for a variation Case study: The asphalt verge dispute Under the 1999 Yellow Book, a “variation” is defined inSubclause 1.1 as any change to the employer’s requirements,or the works instructed or approved under Clause 13. One of the central issues in Uniform centred on installingsewer infrastructure. 5.Tender documents– Although the evidence on the recordwas limited, there was some indication that the drawingscontemplated the sewer being located within a strip ofgrass, gravel or lightly surfaced land immediately adjacentto an asphalt road (commonly referred to as a verge). To claim for varied works, a contractor will ordinarily need todemonstrate: 1.A valid instruction– The engineer must issue aninstruction (or approve a proposal) in accordance withClause 13. Engineers commonly issue directions throughcorrespondence, meeting minutes, drawings, sketches orsite communications. As Subclause 3.3 contemplates thatinstructions will be issued in writing, contractors would bewell advised to create proper records and confirm any oralinstructions in writing – especially if a “no oral variation”clause exists. An engineer’s or employer’s failure to objectto the contractor’s design or execution of the works doesnot amount to an instruction. 6.Preliminary design– The contractor’s preliminary designshowed that the sewer would run through the verge. 7.Requirement for site investigations– The contractplaced responsibility on the contractor to investigate thesite, including borehole data and hydrological conditions.The employer’s requirements further made clear that onlylimited ground investigation had been undertaken and thatthe contractor was deemed to have satisfied itself that ithad sufficient information regarding the ground conditions. 2.A genuine change in scope– Establishing a variationrequires a clear and reasoned articulation grounded in aproper interpretation of the contract, identification of theoriginal contractual scope, a comparison with the relevantinstruction or change, and a coherent explanation of howand why that instruction departs from the agreed scope. 8.Final design/execution– Ultimately, the sewer wasinstalled directly beneath the asphalt roadway rather thanthe verge, thereby requiring extensive cutting, excavationand reinstatement that the contractor claimed wasunanticipated. 9.Claim– The contractor claimed this was a variation.Crucially, the engineer supported this view, acknowledgingportions of the work as variations and approving paymentrecommendations. 2.Review risk allocation for design development– EPCand design-build contracts frequently contain provisionsexpressly shifting responsibility for site investigation,design development and verification of preliminaryengineering information onto the contractor. Accordingly,even where tender drawings appear to contemplate aparticular construction methodology or alignment, theemployer’s requirements may nevertheless allocate theultimate risk of design development and constructabilityto the contractor. Where possible, contractors shouldundertake the necessary investigations before acceptingthose risks, incorporate appropriate contingencies withintheir lump-sum pricing, or negotiate limitations during thecontract negotiation phase. The lower courts initially agreed. The Privy Council, howev