Advancements in interdisciplinary fields respecting systems and subsystems, devices and components and technologies and architectures have resulted in complex infrastructural developments requiring sustainability. This paper presents a sustainable engineering infrastructure (SEI) model that is expected to serve as a planning, design, development, implementation and management platform for the engineering community. Starting from the preconceptual design phase, a step by step algorithm and system-level SEI model has been developed. The SEI model analyses the project lifecycle with an allowance for on- and offsite recycling processes. All aspects of conceptual design, procurement, materials handling, construction, renovation, disposal, decommissioning, hazardous materials, demolition and recycling are addressed. Appropriate metrics for the engineering project lifecycle are incorporated in the developed SEI model functions. Issues bordering on project viability, reliability, performance, deliverability, maintenance, environmental impact assessment and return-on-investment amongst others are integrated into a common design and analysis pool function. The SEI model is expected to offer an unprecedented design and management leverage for project engineers and managers involved in all kinds of projects and infrastructural developments. Energy, maintenance and the external factors characteristics gained severity indices of 70 - 80% and water resources management, infrastructure design characteristics and the project characteristics have 48 - 74% in managing infrastructure systems. A sustainability index of 0.45 was obtained for the case study reported in this paper. The results of this study indicate that the proposed novel SEI model and sustainability index function promise to transform engineering projects management.