In this paper we argue that the modeling activity in the development of software-intensive systems should formalize as much as possible of the environment in which the application being developed operates. We also show that a rich formal model of the environment helps developers clearly state requirements that might typically be considered intrinsically informal (or non- formalizable in general). To illustrate this point, we show how a requirement for "orderly safe traffic" in a traffic system can be modeled, and we briefly discuss the benefits thereof.