The road is public at a first come first serve basic. The slow Amish horse buggy is a Pennsylvania and Ohio common occurrence and fully legal. I remember the frustrated auto drivers complaining about our blocking the road with our excursion train unloading railfans. When we asked the angry driver if it was a public road, they acknowled, and went back to the cars when we informed them that we were part of the public and we got there first and would be using our part of the highway for the next five minutes. We were within the limits of the law for legal occupation of the public space. Its first-come-first-serve, and only a limited access road has a minimum required speed. Good to get the head-up on the schedule.