Spanning six to eight lanes of traffic that cut through the Schnelsen, Stellingen and Bahrenfeld districts of Hamburg, the A7 is among the largest and most disruptive highways in Germany. The current plan calls for installing a 34-meter-wide and 2- to 3-meter-thick canopy over the A7 motorway in three sections, covering a total of 3.5 kilometers.
The A7 cover in Hamburg won’t be the first roadway to be covered in Germany; other canopies can be found in Düsseldorf and Munich, but the A7 cover in Hamburg will be the largest in Germany. The first of the three sections to be built will be the Stellingen section, which will include 893 meters of wooded parkland and garden plots for Hamburg residents. Future sections will include meadows, pathways and more garden allotments.
The A7 cover is expected to cost €600 – €700 million, and it will mostly be financed by the federal government, but some of the funding will also come from selling city-owned land adjacent to the autobahn that is currently being used by gardeners to private real estate developers. The gardeners who are displaced from their plots will be given new plots on top of the green roof canopy. Construction on the A7 cover is set to begin in 2012.
Via Hamburg Green Capital
It's great for noise reduction. And it's definitely good for moving air pollution out of the city. But remember that if you need energy to filter the polluted air then you need a pollution spewing power plant somewhere to provide that energy.
Another valid point (which I am borrowing from jtravism) may be to allow sunlight in at intervals throughout the Green roof. That long of a covered space may have psychological impacts over time. Couple this with the need to let exhaust escape and I think form may need to follow function. However, I am totally on board. Highways are conducive of many pollutants: noise, air and aesthetic.
Great windfall for neighbors who can stand the racket and dust in the meantime, not to mention having bought cheap properties for the inconvenience of living next to the freeway. It will be a lovely neighborhood, with extra O2 for Hamburg from the green spaces. I'm sure the Germans (or their tunneling Swiss neighbors) have all kinds of filtration engineering available - from those long tunnels they've drilled for the mountain freeways.
The A7 will continue to carry the same amount of traffic for that 3.5KM distance. Where will the exhaust gasses go then?