TECHNICAL | ITA/RISK MANAGEMENT


Digital Models


While a new section to the Code, the section on ‘Digital Models’ is relatively short. It calls for all project parties to help develop and maintain accurate such models to help with managing risks – and looking after them is seen to be part of ‘risk management’ of projects, not only a feature of project management. How complex such models may be needs some


thought, being reflective of the complexity, extent and context of the underground works, perhaps including: boundary conditions; 3D layout and structures; geology; worksites; phasing of works (sequencing, logistics – such as variations with time, the so-called 4D aspect of Building Information Models (BIM)); instrumentation and monitoring; and, as-encountered geology and as-built structures. In discussing the geology and ground behaviour,


respectively, the authors recommend that representation of ‘uncertainty’ needs considered for the digital model. While not specifically mentioned in the Code,


with so many potential variables and possibilities in deciding upon digital models, and highly variable experience in the relatively new and still rapidly developing aspect of technology, this should be seen as a further area where clear, collaborative, and consistent communication is necessary – for BIM means many things to many people. The short section on digital models concludes by


recommending there be regular formal reviews and updates to the digital model.


Stages: Design & Construction Information sharing and documentation are vital mechanisms to the design and construction stages, not only for handover of formal information between those parties focused most upon them but also passing the


necessary details between those different players active within each stage, such as transferring details between designers, or between contractors. Those multiple interfaces need managed and the


transfers must include handover of Risk Assessments and Risk Registers. The Code says that consultants need to perform Design Assurance – checking, measuring and verifying the methods selected, but that adjustments are possible to suit evolving findings in the context of risk assessments. The assurance is also “to ensure that the assumptions of the design will be verified and validated during construction.” For the construction stage, the Code discusses the


needs under themes of pre-construction activities, risk management procedures, staff and organisation, constructability, methods and equipment, management systems, independent construction supervision, and management of change. On management of change, the focus goes straight


to any changes in design and/or working methods that result in “material change in risk” and specifies that the insurers are to be told as soon as possible Likewise, value engineering proposals (such as to


reduce time/cost) need documented, with advantages and disadvantages, including what changes may be needed in Risk Assessment and the Risk Register – all to go for client pre-approval before any implementation. This also covers the procedure for anything the client may wish to have changed. Encountered ground conditions, too, need constant


monitoring, consideration and documentation to assess how close or otherwise they prove to be compared to the expectations that guided the design and also construction plans. As such, the Risk Register is a document of constant reference and use, core to a project’s concept, design and delivery, and be no means ancillary. The opposite.


SPOTLIGHT: DEVELOPMENT AND PROCUREMENT The 3rd edition of the Code of Practice for Risk Management in Tunnel Works sets the development stage of a project to include


feasibility, site and ground investigations, option assessments, and initial designs. It states that the client needs to set enough time and money for the investigations and to then prove technical viability of the tunnels before any further step might be taken. On site and ground investigations, again competency is emphasised – for their arrangement to match the needs of the scale


and complexity of the envisioned underground works. They should be phased by the client to progressively develop a greater understanding of the topography, geology and hydrogeology while working to local standards or, where none exist, elected international standards. Either way, documentation is vital, including notes and reasoning should there be departure from standards, codes or practices. The picture needs time to develop and resources spent to enable it to do so. From that, areas and aspects needing further


investigation will come to be known and also practical risks, for construction options. Risk and constructability also feature in parsing alignment options for tunnels, including their broad, indicative effects for relative cost and programme times required. Sensitivity analyses are needed on the cost and time dimensions of the options, which are aspects of a risk-based approach to project development, all for the client to “determine a technically and commercially viable preferred option.” For the chosen option, a dedicated Risk Register is to be prepared, with proposed ways to address risks; plural, if more than one options is taken forward.


Then onto the procurement stage with all this information, matched to a reference design and the elected form of contract, shared with interested contractors. The term that dominates the section on procurement is documentation.


26 | September 2023


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