Overhead vs Underground: comparing high voltage transmission infrastructure
This fact sheet compares the impacts and technical aspects of overhead and underground high voltage (330kV-500kV) transmission infrastructure.
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As transmission projects grow in scale and complexity, owners and investors need greater confidence that they can meet technical and commercial requirements while keeping delivery on track.
Drawing on assurance frameworks refined over many years delivering major transport projects, Aurecon explores what transmission owners can learn from the sector and how Owner’s Engineer (OE), Independent Verifier (IV) and Independent Certifier (IC) roles can reduce risk, strengthen decision-making and improve cost control.
While not every project will need all three roles, the right approach is informed by understanding a project’s risks, delivery model and stakeholder needs, then defining an assurance strategy with the right roles, responsibilities and interfaces for that project.
While Owner’s Engineer (OE), Independent Verifier (IV) and Independent Certifier (IC) roles can all provide assurance, they serve different purposes.
The OE works on behalf of the asset owner, strengthening the owner’s technical capability and bringing a whole-of-life and operability perspective. This means considering questions such as how the asset will operate, how it will be maintained and whether design decisions will deliver the best long-term outcome for the owner.
The IV has a different remit. Its role is to independently check whether the design complies with the contract documents, technical specifications and relevant Australian or international standards. The focus is deliberately objective: is the design compliant or not? By identifying compliance issues early and communicating them clearly, the verifier can help the broader project team resolve issues before they result in significant redesign, delay or additional cost.
The IC can extend assurance further into construction, determining whether the asset has been built in accordance with the agreed drawings, specifications, standards and contractual requirements. Depending on the contractual model, the IC may also make independent determinations on matters such as third-party agreements, interfaces or disputes.
In this video, learn how OE, IV and IC roles de-risk transmission projects, prevent duplication and support efficient delivery.
One of the clearest lessons from major transport projects is that assurance needs to be planned early.
Each role should have a clearly defined outcome, with responsibilities and interfaces mapped before delivery begins. An IV might, for example, be responsible for design compliance, while the IC focuses on construction verification, interface agreements, third-party agreements and contractual determinations. The OE can then remain focused on the owner’s technical and operational interests.
Problems can arise when an additional assurance role is introduced later without reconsidering the wider governance framework. If both an IV and IC are reviewing and certifying the same design, several parties can end up commenting on the same issue without providing additional assurance.
This duplication does not necessarily reduce risk. It can lengthen review periods, add cost and create uncertainty about who is responsible for the final decision. The starting point should therefore be the assurance outcomes the project needs, followed by selecting and scoping the roles required to achieve them.
This video explores how the OE, IV and IC can work as complementary roles, with clear responsibilities to support efficient delivery.
Independence can be particularly valuable where there is a natural commercial tension between the asset owner and contractor.
An IC does not represent either party’s commercial interests. Its role is to consider the facts, contractual requirements and technical evidence, then make an independent determination. Both the owner and contractor can therefore rely on that decision knowing the certifier has no commercial outcome at stake.
This can help prevent technical or quality matters becoming bargaining tools within wider contractual disputes. For that reason, an IC should not necessarily be viewed as another gateway or hurdle. When the role is established well, independent certification can help resolve issues objectively and allow delivery to progress more efficiently.
An OE can then provide advice on what would be the best outcome for the asset owner whereas an IC or IV is primarily concerned with whether requirements have been met.
Good assurance is about identifying material issues early enough for the project team to respond, not just completing a review at the end of a defined review period.
For example, a designer might submit a package to an IV with a 10 or 20-day review period. If the IV identifies a significant non-compliance on day two, raising it immediately allows the designer to begin addressing the issue rather than waiting until the full review period has elapsed.
That early intervention can prevent design teams progressing work on the wrong basis and potentially avoid substantial rework later.
The IV therefore provides more than an additional check. Used well, the role becomes an early intervention point between design development and subsequent project approvals, helping major issues surface before they become embedded in the program.
Assurance ultimately depends on professional judgement, but artificial intelligence (AI) has the potential to help teams exercise that judgement faster, with access to more accurate and timely information. Major projects manage large volumes of complex project and stakeholder requirements, which can lead to issues emerging late in design or delivery when they are more difficult and expensive to resolve.
By extracting and classifying requirements, linking design documentation to assurance activities and identifying missing evidence or unresolved interfaces, AI could help provide a more complete and current evidence base. This allows project teams to focus their expertise on interrogating material risks and resolving high-risk issues earlier.
As transmission projects are divided into more contracts, geographic based packages and technical packages, the number of interfaces increases. Each additional organisation may bring different processes, responsibilities and commercial priorities. Interface agreements, third-party requirements and dependencies between packages can therefore become sources of project risk.
A well-designed assurance framework can provide a more holistic view across those interfaces.
The OE, IV and IC can each contribute in different ways, helping ensure that individual package requirements do not unintentionally take precedence over the needs of the broader project. Independent administration of key interfaces and agreements can also give owners greater confidence that issues are being considered consistently across the program.
The aim is to create an assurance framework where each role has a clear purpose, information moves quickly between parties and the different functions work together towards the successful delivery of the project.
In this video, see how assurance roles manage interfaces, maintain consistency and reduce risk across complex transmission projects.
OE, IV and IC roles provide different but complementary forms of assurance. This table shows how each role advises, verifies or certifies, from protecting the owner’s long-term interests to checking compliance and independently determining contractual outcomes, helping project teams define clear responsibilities and avoid costly duplication.
| ADVISES | VERIFIES | CERTIFIES |
|---|---|---|
| Owner's Engineer (OE) | Independent Verifier (IV) | Independent Certifier (IC) |
| Owner’s advocate | Technical compliance assurance | Contractual outcome assurance |
| Trusted technical adviser providing project-wide oversight, advice and risk management. | Provides objective assurance that design, construction, testing and commissioning activities comply with agreed requirements, standards and approvals. | Provides independent certification and determination where contracts require an impartial assessment. |
Key responsibilities
|
Key responsibilities
|
Key responsibilities
|
| “Is this the right decision for the owner and the long-term success of the project?” | “Has the project been designed and delivered in accordance with the agreed requirements?” | “Has the project achieved the agreed outcome, and can all parties rely on that assessment?” |
The value of assurance comes from designing a governance framework where each role has a clear purpose. For transmission owners, that means planning OE, IV and IC roles from the outset, with scopes that complement rather than duplicate one another.
The right mix of roles should reflect the project’s specific risks, delivery model and stakeholder needs. Done well, this can strengthen decision-making, reduce delivery risk, control cost and give owners, contractors and investors more confidence as projects move through design, construction and certification.
Aurecon is a market leader in the energy sector providing advisory, design, delivery and asset management services spanning all phases of the project lifecycle. Reach out to our team to discuss how Aurecon can help you design assurance frameworks that maximise value across complex transmission projects.
Industry Director, Transmission & Distribution – Australia
Delivery Advisor, Transport & Energy – Australia
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