This essay is based on interviews and observations in more than twenty cities and localities around the country and on the increasing literature and data about the homeless problem. The approach is a set of three scenarios presented in the present tense even though our time frame is 10 to 20 years hence. The scenarios are not intended to be mutually exclusive; parts of each could occur simultaneously. The scenarios, we think, are both plausible and thought-provoking. Some elements assume no change in public policy; others are built around specific public policy interventions. Following the scenarios we offer some commentary and inferences for public policy.
Question: How to understand the conceptual metaphor of "built around"? Public policy intervention? Policy intervenes, or policy is intervened? In other words, is the word "intervention" like challenge in Hong Kong's challenge in which Hong Kong could be challenged or Hong Kong is challenging to others?
To me, it only has the sense of 'intervenes'- the policies will have an impact on the city around them.