It seems the aliens responsible for the famous crop circles of the past have updated their methods to reflect the increasing urbanization of the world population. Anywhere there is pavement, chances are it has been "street striped."
So far, there are no photographs of the aliens in action. In the crop circle days, no one really expected photos since the locations were exclusively rural. With the stripes located in denser population areas and the increase in cameras, they're even in our cell phones, the lack of photos may indicate that aliens have advanced technology such as a cloaking device.
No one knows what the stripes mean or if aliens will show up to interpret them any time soon.