Concrete expressionism

Expanses of concrete or asphalt are a challenge - all that grey can kill a picture.  Fortunately, grey is just a subtler version of white, a mixture of all colours, so you can choose which ones to emphasize.  I picked purple and yellow for the tarmac at Vancouver airport on a late fall day, and blue and brown for a bird's-eye view of an alleyway descending into an early dusk in Edmonton.