It is defined as a "guide for the economic selection among technically feasible alternatives for the purpose of a rational allocation of scarce resources.
Economics as a social science answers those questions and is defined as the knowledge used for selecting among "...technically feasible alternatives for the purpose of a rational allocation of scarce resources.
[3] As a subdiscipline practiced by civil engineers, engineering economics narrows the definition of the fundamental economic problem and related questions to that of problems related to the investment of capital, public or private in a broad array of infrastructure projects.
[4] Civil engineers under constant pressure to deliver infrastructure effectively and efficiently confront complex problems associated with allocating scarce resources for ensuring quality, mitigating risk and controlling project delivery.
[7] They must also be capable of integrating these economic considerations into appropriate engineering solutions and management plans that predictably and reliably meet project stakeholder expectations in a sustainable manner.