Right-of-way, meaning the right for one person or vehicle to pass before another, is usually hyphenated, but leaving it unhyphenated is not a serious grammar mistake. In fact, British publications are wont to omit the hyphens when right-of-way is a noun.
Examples
For example, these writers use right-of-way correctly as a noun (ignore the bizarre illogic of the claim made in the third example):
Kindness does not get the right-of-way on these streets and tunnels. [Lost in Translation]
Officials said the oil spill has been contained along the pipeline’s right-of-way and in nearby pools of stagnant water. [Wall Street Journal]
It’s difficult for drivers along Florida Avenue in Northwest to give the right-of-way to on-foot pedestrians if they can barely make out the sign telling them to do so. [Washington Post]
And the much rarer phrasal adjective form is hyphenated as well:
When we walk, we have to trust that drivers and cyclists will observe pedestrian right-of-way laws. [Cycling Spokane]
