Well, the highway is Autopista del Coral, and it's a highway from la Romana to Punta Cana. From Santo Domingo to la Romana is Autopista del Este. This one is not YET concluded and won't be so son either. It ends up like 10 kms before getting to la Romana, and there is no Romana overpass (yet) even though SOME work has been done. Also, San Pedro overpass is not a 4-lane highway yet, only a 2-lane highway.
Also, as far as San Pedro overpass is concerned, I have measured transit time and it's the same time to go through San Pedro city and to drive on overpass. It's about 10 kms longer using overpass.