Barcelona is covering a road bridge with concrete that eats pollution

Image: BCQ.

Converting horrible bits of concrete transport infrastructure into green spaces has become a bit of a trend recently. In Hamburg, there's talk of turning a motorway into a park; then there are the dozens of attempts to piggyback on the success of New York's High Line by creating pedestrian walkways and parks.

But one Barcelona bridge is trying something a little different: it's keeping its cars, but introducing a host of sustainable green technologies to make it much, well, nicer.

The Sarajevo bridge is a member of what is surely the grimmest category of urban infrastructure: a road bridge over another road, to the north of the city centre. At the moment, it looks like this:

Under a plan commissioned by the city government and developed by architects BCQ, however, it's due to be transformed. It'll still be a road bridge, but its surface will be paved with pollution-eating "photocatalytic concrete". The pedestrian walkways will be widened so they can be used as plazas, while greenery-covered walls and a canopy will shield users from the noise of the six-lane road below. The bridge will also be entirely self-sufficient, with solar panels on the bridge powering LED lights.

Here's a mock-up of the new bridge as seen from the road below:

And a cross-section:

Click for a larger image.

There's no completion date for this project, which is one of a number of schemes intended to green currently unattractive bits of Barcelona. But it does have the backing of the city government, so unlike so projects that come with cool concept images attached it may actually happen.

We're most fascinated by the smog-sucking concrete, which uses the energy of the sun as it strikes the road to break down pollutants into neutral substances like water, oxygen and nitrates and sulfates; these stick to the surface, and are later washed away by rain.

This probably won't make much of a dent in the pollution produced by the roaring highway below, but every little helps. 

All images: BCQ Architects.

 
 
 
 

On Walter Benjamin, and the “Arcades Project”

Passage Verdue, Paris. Image: LPLT/Wikimedia Commons.

In 1940 a small group of refugees were turned away at the French-Spanish border. Having fled the Nazi invasion of France, they hoped to find safety in Spain. One of their number, a German-Jewish philosopher and writer, intended to have travelled onwards to America, where he would certainly be safe. So distraught was he by the refusal he met at the border that he took his own life.

The writer in question was Walter Benjamin, the prominent critical theorist who has contributed so much to our understanding of urban society, and he died with a manuscript close at hand. When asked previously if the briefcase of notes was really necessary to a man fleeing for his life he had replied, “I cannot risk losing it. It must be saved. It is more important than I am.”

The work that Benjamin died protecting was the Arcades Project. It was to be his magnus opus, intended by the author to illuminate the contradictions of modern city life. But it was never finished.

To Benjamin, the subject of the work, the arcades of Paris, were relics of a past social order, where consumerism ruled. The arcades were a precursor to the modern mall, lined with all sorts of shops, cafes and other establishments where visitors could buy into the good life. The area between these two lines of businesses was covered with glass and metal roofs, much like a conservatory: it gave visitors the high street feel in an intimate, sheltered and well-lit setting. You can still find examples of such places in modern London in the Burlington and Piccadilly arcades, both off Piccadilly.

Such arcades proved hugely popular, spreading across Europe’s capitals as the 19th century progressed. By Benjamin’s time, though, his type of shopping area was losing custom to the fancy department stores, and in Paris many of them had been obliterated in Haussmann’s city reforms of the 1850s and ‘60s. Whereas Parisians could once visit 300 arcades, now only 30 remain.

Through his research Benjamin started to see the arcades as representative of a pivotal moment in social history: the point when society became focused on consumption over production. Buying the latest fad product was just an opium, he thought, dulling senses to the true nature of the world. By bringing light to this, he hoped to wake people up from the consumerism of the 19th Century and bring forth some kind of socialist utopia.


He also warned that this shiny veneer of progress was hiding the true state of things. Instead, he revered crusty old cities like contemporary Marseilles and Moscow, where social life was more honest. In this way, Benjamin contributed to the intellectual movement focused on stripping away the excess of revivalism, standing alongside architects such as Le Corbusier. 

Through his newspaper essays throughout the first half of the 20th Century, Benjamin also became one of the first thinkers to focus on urban isolation. His suggestion that we can be most alone when among such a dense mass of other people is something many in modern cities would sympathise with. His work wasn’t all doom and gloom, however, as he saw cities as our salvation, too: laboratories from where society’s problems can be worked out.

It was 2000 before an English translation of the unfinished the Arcades Project was published, but by then the work had already had a significant impact. Just as he stood on the shoulders of giants such as Baudelaire and the Surrealists, modern thinkers have drawn on his work. Benjamin's concerns about common architectural forms can be seen to inspire modern architects such as Laurie Hawkinson, Steven Holl, Tod Williams and Billie Tsien.

The city of Paris itself was as much a part of the Arcade Project’s inspiration for Benjamin as was his intellectual predecessors. In his letters he repeats that it felt “more like home” than Berlin, and his days were spent marvelling at how the old and the modern exist together on the Parisian streets.

How groundbreaking the Arcades Project really was is hard to say. The fact it wasn’t finished certainly scuppered Benjamin’s plans to wake society up from its consumerist slumber, but that doesn’t make the work inconsequential. His fairytale of steel and glass is as much about the relationship between its author and Paris as it is a theoretical work. By putting the city as the main subject in human’s social history he laid the groundwork for future generations of thinkers.

Benjamin was lost to the tragic tide of the 20th century history, and his death marked the end of the project which could have changed the way we think of the urban landscape. Even if you shy away from the grandiose or don’t buy into his promises of socialist utopia, reading the work can still offer some eclectic factoids about 19th century France. At any rate, it must be acknowledged that the man gave his life to the betterment of society and the cities in which we live.