The M-30 is an inexhaustible source of urban projects. The last one, the installation of vertical gardens in some of the retaining walls that surround the road. Green infrastructures have seen their presence grow in modern urban planning. What does science say about its benefits?
Calle 30 Natura, as the project has been called, is still in the preliminary phases, although it will have a pilot project that will vegetate a length of 400 meters in the northern segment of the road, but the intention of the council is to extend the project to other similar walls on the perimeter of this ring road.
The pilot will cost 3.8 million euros, which could rise to 30 if it is decided to extend it to the rest of the M-30, thus covering, according to the Madrid city council itself, an area of 100,000 square meters.
In addition to this new green infrastructure, the project will have sensors to measure the impact of vegetation on the levels of pollution in the environment.
As we well know, plants absorb carbon dioxide and expel oxygen, but the link between them and our health and well-being goes much further. Vegetation not only absorbs carbon dioxide but is also capable of retaining particular matter, small polluting traces of different diameters that affect our respiratory health.
Traffic is one of those responsible for both CO2 emissions and volatile particles in urban environments. Using vegetation as a barrier between the emitters and our own lungs can help improve the health of one of the traditionally most polluted cities in the country.
No less important than environmental pollution is noise pollution. In this the vegetation also plays a fundamental role. Urban roads such as the M-30 present a problem for those who live in its surroundings. To avoid excessive noise, it is common to resort to various strategies, from side panels to full burial.
Several studies have shown how vegetation significantly attenuates the noise from cars that reaches those who are on the roadsides.
Avoiding noise is a good idea for our hearing health, but also for our mental health. Perhaps for this reason, a good part of the health benefits associated with green infrastructures have to do with psychological well-being and mental health.
The measure therefore seems effective. The question that follows is whether it is efficient. The 30 million invoice invites us to stop and analyze this aspect and it is not clear if the expected cost of the project includes its maintenance. Vertical gardens are expensive and difficult to maintain, especially in this case located in the middle of one of the busiest roads in the town.
Of course, the measure has also been presented as a way to combat graffiti on the walls that surround the road. The money saved in this regard will hardly offset the cost of maintenance, but it could alleviate it to some extent.
Some critics consider that there are areas of the capital where the marginal benefit of introducing green infrastructure would be greater. When such a project was implemented in Mexico City, some critics pointed out that these gardens only served to make the experience of driving on the roads adorned with these gardens more pleasant.
What vertical gardens do not solve.
Although green infrastructures such as vertical gardens bring advantages for the health and well-being of people, it must be taken into account that there are problems associated with urban highways that cannot be solved with them.
One of these problems is that of heavy traffic, which could even worsen in places where maintenance works involve the regular closure of lanes. These measures do not necessarily imply an improvement in road safety, nor do they help to improve connectivity between the different neighborhoods separated by road infrastructure.
Even so, the growth of cities implies the need to introduce green areas in them that make them more habitable. The effect on health of these measures translates into lower health costs, so they are long-term investments, with profitability, yes, very difficult to measure.
Image | City of Madrid
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