WINCHESTER — The southbound Interstate 5 onramp at Exit 129 is now open, signaling that a $22 million interchange project that began 16 months ago is nearly complete. The project included moving an overpass and realigning Del Rio Road to improve the flow of traffic to Umpqua Community College and improve access to undeveloped land. Oregon Department of Transportation spokesman Dan Latham said Thursday workers still must do some paving and put down lane markings, but construction for the most part is done. “There will just be nighttime lane closures through sometime next week,” Latham said. He said the closures …