That is an excellent question. At Metrolinx, we basically look at it in three ways in terms of how we make project selection decisions in the end.
The first level is the plan stage, when we look at all the needs—the linkages and the land use—and try to identify what the overall plan is for moving forward in the short, medium, and long term. The second stage I would call the program level, when we go through a process that we've called our prioritization process. We look at the social, economic, and environmental benefits of different projects, and compare them to each other so that we can provide some advice to our board of directors about which projects provide the most value in the end. Value isn't just in the sense of the dollar value, but in terms of the whole range of social value, environmental value, and economic value.
Then at the project level, we also have business-case analysis that we do—I think that's what you referred to—where we look at the cost benefit. We basically use that tool to look at different ways of delivering a project. If you adjust the project in a certain fashion; or if there are different values or results you get from that adjustment that are better than the original concept; or if you stage it differently; what are the different impacts of your phasing plan? If you deliver it in different models, what's the value you get from your different delivery mechanism?
There's a plan level we do, with prioritization among projects, and then business-case analysis within a project. It's important to be thinking about an evidence-based approach at all of those levels.