Clubman7 and Goff both come up with the correct answer, Breadcrumbs.
JasonK wins the prize for most incorrect rejection of the correct answer.
According to Mrs JasonK both the Dwayne and StephenSLR win bragging right for funniest reply (Adelaide, she grew up there and it is so damn close to reality it is not funny) and the joystick comment from StrphenSLR.
Seems to be breadcrumbs, but because I am very often driving 'out and back' along the same routes, I am seeing these things almost all the time. Thanks for your help and the hilarious comments!