Infrastructure systems are increasingly influenced by external changes, for instance technological, institutional, political and socio-economic changes. Keeping infrastructures flexible, reliable and affordable under these ever-changing circumstances is a challenge.
Researcher Austine Ajah argues that infrastructure systems can only be truly flexible and reliable if all potential uncertainties are identified, and if flexibility and reliability attributes are incorporated as performance indicators. These allow timely evaluation and adjustment during an infrastructure’s life cycle. Ajah has defined a specific set of such indicators: Flexibility, Reliability, Availability, Maintainability and Economic (FRAME) performance indicators.
“You need to capture the potential external and internal changes as uncertainties in your infrastructure systems design,” Ajah summarises. “Including such performance indicators early in the design phase will help you do so. After all, it is this stage that offers the greatest degree of freedom to influence the output of the system being designed. If you don’t take into account uncertainties, your infrastructure system will always be negatively affected.”
To improve infrastructure systems engineering (ISE), Ajah and his colleagues draw inspiration from process systems engineering (PSE), a branch of engineering that is technical rather than socio-technical in nature. It is therefore less complex but much more flexible than ISE. “In industrial batch systems, for instance,” says Ajah, “the trend is towards modular systems. These are usually much more flexible: depending on factors such as market demand, you can tune the individual batch modules and thus adjust your production. We are now exploring how this approach could be extended into the ISE domain.”
Ideally, the approach and framework that have been developed will allow ISE designers, at an early stage, to define uncertainties and use these to allow for various future scenarios. “In the literature,” says Ajah, “a system is assumed to be either fully functional or fully dysfunctional. This is what we call a two-state, dual-performance model. In reality, however, most ISE systems have more than two states. This is what we try to capture in our multi-state, multi-performance model. This Reliability, Availability and Maintainability (RAM) model could act as an early RAM decision support for infrastructure systems designers.”
Both the RAM model and the PSE/ISE comparison are unique in ISE, as Ajah points out. Companies in the field have reacted positively so far. “Pilots have proven fruitful, for instance in offshore infrastructure design. The next step is to transform these experiences into useful decision-making tools.”