A bibliometric study, published in 2019, of the evolution of research regarding sustainable urban infrastructure emphasizes that this concept continues to grow in the research community and change in scope as technology improves. According to the College of Engineering and Applied Science of the University of Colorado Denver, urban infrastructure refers to the engineered systems (water, energy, transport, sanitation, information) that make up a city. Not solely based on evaluating utilities, sustainability efforts in urban infrastructure seek to combat global warming and municipal waste, as well as encourage economic prosperity. Socioeconomic implications of these efforts often involve policy and governance in the implementation of sustainable infrastructure, and their variation results in different programs sized on national, regional, or more local scales.