Can Green Walls Beside Highways Actually Reduce Temperature and Pollution?
A new project to turn a highway structure into a living wall in Buenos Aires. Photos: Paula Alvarado.
The Buenos Aires government is doing a six month tryout of how green walls perform in the city's highways as noise, temperature and pollution mitigators. Installed inside horizontal tubes filled with water and nutrients, the first seedlings were planted in the exit of a route that connects the southern part of the city with the suburbs. But, do green walls next to motorways do any good at all?The idea is not new, though certainly not as extended as living walls and vertical gardens in buildings.
In the US, there was a project of an isolating green wall in a highway in Wisconsin in 1994 (which did not end up well) and there's a new one in Ohio announced early this year, according to Discovery News; while Mother Nature Network reports that in Singapore some highway structures have been covered with plants.
It seems weird though that there's little evidence (at least that I could find) of the actual results these can have in lowering the noise, contamination and temperature of the highways as they say they do.
The Buenos Aires project (via TuVerde) is closer to the Singapore idea, as the government has covered existing walls in the highway exit with plants.
And the question arises: given the enormous amount of cars that go through this exit every day (Buenos Aires doubles its population with people from the suburbs every workday, most of them arriving by car or bus, many from the south), How much noise and contamination can this actually absorb?
According to the same article from Mother Nature, green walls don't usually do much for pollution in cities, although they do help with temperature and, of course, aesthetics. Perhaps the main achievement of the Buenos Aires project will be looks, and that's not bad.
Do you know of any other project of this type and its results? What do you think?