Right of way.
It means you have the right to pass.
But pedestrians do not always have the right of way. If they are crossing when it says "Don't Walk" they do not have the right of way.
A right of way also applies to real estate. A utility line that crosses a farm for example might entail a right of way on the part of the company or a neighbor who has been crossing your property to get to his might have estanlished a right of way.
http://dictionary.reference.com/browse/right%20of%20way