On Sunday, I braved the cold to drive out to the edge of London with Tim Bowditch and Nick Rochowski.

Tim and Nick have been taking photos of the M25 - or, more specifically, they have been taking photos underneath the M25.

(A quick note to say that [obviously] these aren't Tim and Nick's pictures - these are, as always, low quality digital photos from my phone)

All around the motorway are underpasses - some of them are small tunnels that allow the road to cross streams, others are more traditional underpasses that bridge small roads or footpaths, and some, like in the above photo, are for farmers to drive tractors between their fields, divided by the M25.

This tunnel had some unique graffiti with a big focus on anal concerns.


And the usual hastily sketched cocks.

Tim and Nick are trying to avoid the graffiti - their photos will highlight the material, abstracted nature of the architecture.

But Nick said something which, for me, connected the graffiti to the architecture in an interesting way. He was trying to rub off a chalk mark on one of the walls and he said that the tunnels were like the surface of the moon - any human trace would be preserved for many years, protected from the elements that would normally wash them away.

I was also thinking about "bad" graffiti (tags, lewd comments, drawings of cocks), and how it tells you a lot more about the social history of a place than "good" graffiti (skilful spray-paint work, big colourful letters etc.). Like the EUROZ tag in the photo above. When did the tagger choose his name? Surely before the crisis in the Eurozone? Or is it a comment on the economic situation? If I was a tagger I'd go for RENMINBI (the Chinese currency) in the current climate.

We ended the day here, a large underpass over a river and public footpath. These triangular areas of negative space caught our eyes immediately - unintentional masonic symbols brought about by the extreme functionalism of the architecture.

These are the sort of dead zones that feel almost haunted - the M25 is right above you, you can hear the suspension in the bridge working constantly - echoing, clunking, swishing noises.

From far away the road sounds like the sea. Up close it is more like factory - the noise never ceases, inseparable from the functioning of the motorway. Maybe the noise is the product? Or maybe it is a symptom? The tinnitus ridden ear canal of a giant.

The camera Tim and Nick are using for the project has an achromatic digital back. That means that it can take photos in almost total darkness because it picks up the whole light spectrum, including infrared waves.

The camera takes in a huge amount of visual information, with the surface of the concrete rendered in textural detail that is breathtaking - zooming in on a few hi-res images on the computer is like taking a magnifying glass to the surface of another planet.

The downside (on a cold January night) is that the photos need long exposures - up to an hour. And this is then doubled by the in-camera processing.

On the other hand, this long, enforced habitation of dead space becomes an extreme meditation on the built environment. Squatting in the cold, on a muddy bank, for two hours, certainly focuses your mind on what's around you.

This focused attention is always there in photography - especially landscape or architectural photography. Noticing and planning and understanding the shot you want to take is as important as your technical skill with the equipment.

I suppose it is a sort of enforced mindfulness, or this idea of 'the importance of paying attention' that I have written about before.

Also, the language of photography allows Tim and Nick to talk about embarrassing, romantic ideas like beauty or the sublime in technical terms. The need for a certain depth of field or exposure time is a technical appreciation of the task of capturing such a landscape in one image.

We had to give up on the last shot, it was getting late and they couldn't get the angle that they both understood to be the essence of the picture they wanted. Nick said, 'it's so frustrating - you can see it in your head, but it just isn't there'.

I'd say that this ability to conceive of a unified image that isn't there is one of the basic functions of human understanding. Without it we wouldn't be able to think about ideas that we couldn't directly perceive: like the idea of 'London' as a single place; or 'Me' as a single identity; or the M25 as a single road, circling the city endlessly, chasing its own tail. Round and round and round.