Usually with street lettering the words are first traced out in yellow before the white paint is finally applied, offering a chance to check spelling of what is about to be permanently painted. But no. Sometimes the inevitable still happens.
You can take a look at this link from Highways.com of some more fantastic road spelling bloopers.
And if you ever wondered how freehand thermoplastic street lettering was applied, this YouTube video can assist. The spelling is all correct in this video.