Maximize the benefits, but what about the costs?

Popular Mechanics lists their top 10 pieces of infrastructure that "we must fix now:

1. Circle Interchange, Chicago
2. Brooklyn Bridge, New York
3. Canal Lock, New Orleans
4. Water System, Atlanta
5. Alaskan Way Viaduct, Seattle
6. Lake Okeechobee, Florida
7. Dover Bridge, Bonner County, Idaho
8. Wolf Creek Dam, Kentucky
9. Sacramento River Levees, California
10. O'Hare International Airport, Chicago

The benefits seem high but I'm not sure about the costs. I think it would be cool if some economics blog would list the top 10 pieces of infrastructure ranked in terms of net benefits.