Let's say you're the Department of Transportation. What's at the top of your list? Building more lanes on highways? Creating a bike share? Buying more busses? Repaving the streets? Unless your strategy is to win the funding lottery (not likely), you can't do it all.
Of course, most smart managers will choose the projects that accomplish their goals. If success is reducing the commute delay on your highways, then build more lanes. If it's emissions per commute, buy bikes and busses. If it's miles traveled per commute, reduce the speed limit on all of your roads and collaborate with the housing authority to build more homes downtown.