WASHINGTON, May 19 -- The National Railroad Passenger Corporation (Amtrak) issued the following news release: Customers can soon take advantage of additional opportunities to travel on the Piedmont as Amtrak and NC By Train add a daily roundtrip for service between the vibrant commercial center of Charlotte and state capital of Raleigh. Tickets are now available to purchase for travel beginning on July 10. To meet the increasing demand for passenger rail service and provide additional capacity  more