Is it reasonable for a police officer to stop and question a drunk driver in the street?

In light of the public danger attending the reckless and drunken driving of automobiles, it was manifestly reasonable for the officer to step up to the stopped vehicle and inquire of its driver the reason for its erratic operation. "It is now settled law 'that circumstances short of probable cause to make an arrest may still justify an officer's stopping ... motorists on the streets for questioning.' " (People v. Rios, 140 Cal.App.3d 616, 621, 189 Cal.Rptr. 634.)