WASHINGTON - President Barack Obama on Friday nominated new administrators for the Pipeline and Hazardous Materials Safety Administration (PHMSA) and the Federal Railroad Administration, the White House said. Marie Therese Dominguez, an assistant secretary at the Defense Department who has worked at the Transportation Department and National Transportation Safety Board, will be nominated as head of PHMSA, the White House said. Sarah Feinberg, a former White House adviser, will be nominated as head of the Federal Railroad Administration. Both positions require confirmation from the Senate.