This picture seems to have done extremely well on Flickr, and I have had a few private messages asking how it was achieved. Who am I to halt the learning process?

The process was simple enough. I was armed with a Nikon D300, Sigma 10-20 lens and a tripod.

I framed the shot and narrowed the aperture down to f13, to keep things nice and sharp. As I was on a tripod, I had no need to mess things up with a high ISO, so kept it at a low 100. I metered the exposure off the building opposite (St.George's Mansions), which gave a 20sec shutter. That was ideal for my needs.

The reality of Charing Cross is that traffic only ever flows one lane at a time. I had to wait for one lane to start flowing before I opened the shutter, then again for another lane, until all the lanes were covered.

That was it! I stacked them in layers in Photoshop and used the "Lighten" blending mode. This brought the light car trails from all the layers into one. Flatten the layers, tweak the contrast/saturation a bit and I was done.