Automobile drivers are responsible for understanding the symbol, even if the meaning is graphically obscure. The marking indicates a sharrow, a lane that bicycles and motor vehicles are meant to share. In fact, the marking indicates the ideal place for a cyclist to ride in the shared lane.
In this photo, cyclists would be riding down the steep hill of Pottery Road, so cars should not be slowed too much by their road-sharing fellows. A cycle path on the other side of the cement barrier accommodates uphill cyclists.