An engineering decision may be technically sound on its own, but what happens when it meets another system, another discipline, or another constraint?

This article examines why technically sound decisions can become difficult when they cross disciplinary boundaries, and why the connections between systems can be just as important as the systems themselves.

When Interfaces Meet

Civil, mechanical, electrical, industrial automation, instrumentation, and process control, and other engineering disciplines often make decisions that affect the same areas of a project.

For instance, a structural beam may need to accommodate a mechanical duct, while electrical services must be routed around both. As these systems come together during design and construction, a change to one can require adjustments to the others. These interactions can become more complicated when changes are introduced, or information is not fully aligned between fields. In fact, improper interfaces between engineering design disciplines have been linked to a significant share of construction change orders. 

interface

According to a 2023 study entitled “Effects of Change Orders on the Budget of the Public Sector Construction Projects in the Kingdom of Saudi Arabia,” there are approximately 26% of 296 change orders across 43 public construction projects which were attributed to design-related issues, including errors and omissions, modifications, inadequacy, and unrealistic timeframes.

interface

While the study focused on projects in Saudi Arabia, the issue of coordination remains relevant to the Australian engineering context. In its 2026, “Industry Partners Series: Managing Risk Before It Becomes Rework”, Engineers Australia highlighted how fragmented project information can contribute to delays, coordination issues and increased risk on major infrastructure projects. 

Together, these examples show why a technical sound design is not always enough. This is what makes interface engineering critical in complex projects. 

Where Gaps Form

The more disciplines involved in a project, the more information and responsibilities need to move between them. This can include design requirements, technical assumptions, approvals, and changes.

interface

When these are not clearly communicated or assigned, an issue can sit between teams without being fully addressed. According to ICON Engineering, an Australian engineering consultancy specializing in multidisciplinary engineering and project delivery, its Interface Engineering & Integration guidance explains that effective interface management requires teams to clearly establish the following: 

  • Responsibilities – who is accountable for each side of an interface 
  • Information – what technical information needs to pass between teams 
  • Timing – when that information needs to be exchanged 
  • Scope – where one discipline’s responsibility ends, and another begins 
  • Traceability – how interface decisions and agreements are recorded 

Gaps can form when these points are not clearly defined or communicated. These possible gaps are not necessarily the result of a technical error within one engineering discipline, but addressing them therefore requires engineering professionals to understand how different parts of a project recognize intersect. Managing these gaps therefore calls for capabilities that extend beyond technical knowledge.  

Working Across Boundaries

Engineers Australia’s 2026 National Competency Standard for Engineering reflects this broader expectation through the following practice areas and engineering mindset: 

  • Collaboration – Working effectively with other disciplines and stakeholders requires engineers to understand different professional perspectives and contribute to shared project outcomes. EIT’s work integrated learning model supports this through industry engagement and research, giving students exposure to perspectives beyond their own discipline. 
  • Communication – Interface work depends on communicating design requirements clearly between the teams responsible for different parts of a project. EIT’s conferences and research activities provide opportunities to communicate developments across the industry. 
  • Management – Managing an interface requires engineering judgement to decide what needs to happen, who is responsible, and when action is required. EIT’s engineering courses and technical webinars address practical decision-making relevant to actual project delivery. 
  • Systems approach – A broader view of engineering considers not only the technical problem, but also the perspectives that shape how it is understood and addressed. This aligns with EIT Dean Indumathi V’s discussion in the All Things Engineering podcast episode, “The Real Value of Diversity in Engineering,” where she highlighted inclusion as a way of bringing different perspectives into engineering. 

Ultimately, effective engineering is not only about getting each part right but understanding what happens where those parts meet. 

References

Effects of Change Orders on the Budget of the Public Sector Construction Projects in the Kingdom of Saudi Arabia 

Interface Engineering & Integration 

National Competency Standard for Engineering 

This article was published October 20th, 2026 and the content is current as at the date of publication.

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