I have encountered this roadblock once, around 11 PM, getting onto Rt 95 from Rt 1 in York, ME. ALL cars were stopped and drivers were asked if they were drinking. I had been, told the officer my version of the truth, that I had a few beers with dinner a few hours ago. He asked me to pull over, had me get out of my car, and perform a few sobriety tests, which I easily passed. After passing the tests, I was allowed to continue on my way. I’ve encountered this once, but I’m not from the area. I’ve heard others say they have seen it there as well.