Keywords: socio-technical systems, interconnected infrastructures, cascading failure, complex systems, civil infrastructures, human factors, institutional factors, hazard mitigation, risk assessment
A socio-technical systems approach to understanding and enhancing the reliability of interdependent infrastructure systems
Civil infrastructures are vital elements of a nation's economy and quality of life. They represent a massive capital investment, and, at the same time, are an economic engine of enormous power. Modern economies rely on the ability to move goods, people, and information safely and reliably. Consequently, it is of the utmost importance to government, business, and the public at-large that the flow of services provided by a nation's infrastructure continues unimpeded in the face of a broad range of natural and man-made hazards. In a continuous search for increased efficiency, our way of life is increasingly dependent on tightly coupled, highly sophisticated networks of transportation, electric power, and telecommunications systems from which essentially all redundancy has been removed. These systems become vulnerable to failure simply through their inherent complexity – and although failure may be predictable – its mode and mechanisms are not. The terrorist attacks of September 11 provided ample and horrific evidence of a previously unimaginable complex system failure. Passenger throughput and airport security, seemingly unrelated to structural performance, were critical in producing the most devastating building collapse in history. Therefore, from a comprehensive hazard mitigation standpoint, it is necessary to look beyond the first-order effects of an event and instead seek to understand the perturbed behaviours of a complex, 'system of systems'. Making these systems inherently more resilient and reliable will require more than just improved engineering and technology – complex socio-technological systems also have critical human and institutional elements that need to be integrated into design and operational procedures.