Sustainability involves multiple environmental, technical, social and economic factors, and such complex analysis requires systemic solutions. Delivery models are key to achieving system benefits and enhancing sustainable development in infrastructure investments. They define the phases of a project, incentive structures, risk sharing and the relationships among the actors in it. They are usually developed early in the project and determine the project dynamics and outcomes. We compared traditional delivery models with systemic ones. We identified and illustrated elements that differ between them through two cases. The contribution is an increased understanding of how systemic infrastructure delivery models can adapt to changes in their environment. We also found that sustainability is vastly under-researched in systemic infrastructure delivery, but that its potential to deliver benefits to PPP infrastructures is substantial.