Engineering projects can be of various types.  One example would be the development of an idea into a product.  Projects of this type involve a lot of unknowns and thus a greater deal of uncertainty.  Construction projects are of a different type.  They start with a design and end up with a physical product that is some kind of a structure.  Construction projects face a lesser degree of uncertainty than a project in which a new product is being developed, unless of course,  a totally-new construction method or equipment is being used.

Estimating costs and revenues as accurately as possible is critical to the engineer's decision-making.  As you can imagine, estimating future revenues is difficult.    This is especially true if the product you are introducing to the market is a new one.  It is also important to account for all kinds of expenses, while you are estimating future costs.  For example, engineers typically consider equipment, material, tooling, and labor costs, while ignoring advertising, promotion, and public relations costs.

The text has a good example of an engineering project in which a new idea was developed into a successful product.  The Toyota Motor Company's Prius story exemplifies the importance of engineering economic analysis in the context of a large engineering project.

It is also important for engineers to understand the importance of a project's profitability versus the overall impact on the financial strength and position of the company as well as cash flow versus profits.  They need to understand that the market value of a company is determined by cash flow not just profits.  Companies with more cash can make more future investments and grow more.