Bridges and viaducts are structures that connect. Their design must obey the flow and passage of vehicles, and that is why there are few reports like those of antihero Robert Maitland: the experience of these structures as something beyond a movement, as a place of permanence, as a cosy space, as a home.

But “viaducts as a living area” could be the subtitle of Skies of Concrete (2015), an essay by Austrian photographer Gisela Erlacher. Unlike the rugged urban jungle of The Concrete Island (JG Balard, 1971), Gisela’s concrete ceilings are surprisingly plastic overpass flats, upbeat and domestic. These are spaces that break usage conventions, often (but not always) appropriated by people who have nowhere to live in the city’s formal or informal settlements. At first they are non-places: apparently abandoned anonymous spots that offer little in terms of habitability, that convey insecurity precisely because they do not have a clearly designated function.

It would be what the French anthropologist Marc Augé calls non-lieux: transitory spaces that we experience when traveling and that we remember only in generic terms. But actually the ceilings in this essay are not non-lieux. The photos point to a very different phenomenon: that of the growing competition for an increasingly scarce and precious urban space, whether in China, Austria or the United Kingdom, contrasting this lack with an occupation that is often designed and admirably managed.

Some images are so incongruous that they look more like surreal collages or hyperreal digital visualizations. Ceramic-roofed houses are squeezed between colossal pillars with no relation to scale, typology or history while children play, indifferent to that obvious overlapping of incompatible activities. Beneath a complex of concrete boards that dance in a choreography of mismatched semicircles, we see a children’s pool with its happy pink toys. In the same photo, cars in a row circulate on a board at half height at high speed, their drivers absorbed and uninterested in what happens in the children’s playground and its green spaces. A hypostyle space, entirely made up of stems camouflaged by vines and topped by concrete capitals, covers a park lined with a landscaping of ages on a terrain of almost organic topography. We are probably on an expressway, but the photographer only shows us the slowed down and contemplative time under the viaducts. Under another complex of three interpolated viaducts, we see a makeshift stable and its many horses with their faces out the door, eager to get out of their cubicles and train on the sand track covered by concrete skies.

It is an urbanism of infrastructures in layers that could cause a short circuit between them, but whose energy does not harm users at various levels – unaware that they are in relation to the other functions of that complex.

This is not a vertical architecture where the floors are programmatically independent: it is a stacking of functions on an urban scale, the potential friction between the programs being mitigated by the colossal scale of the viaducts.