You should take a look at the Madrid Rio project by Dutch studio West8, it's very similar to the mentioned idea in the BBC article: http://www.west8.nl/projects/madrid_rio/
In Summary:
- The city of Madrid buried a 6km section of their ring road
- In this buried section, a total of 46km of roads/tunnels have been constructed
- The above area is now a reclaimed riverbank and a huge park
- IMO, a superb public realm initiative, although I'm guessing not cheap
In Summary:
- The city of Madrid buried a 6km section of their ring road
- In this buried section, a total of 46km of roads/tunnels have been constructed
- The above area is now a reclaimed riverbank and a huge park
- IMO, a superb public realm initiative, although I'm guessing not cheap