Cynthia Quarterman, head of the Pipeline and Hazardous Materials Safety Administration (PHMSA), is planning to step down.
Quarterman, who leads pipeline and hazardous material regulatory efforts within the Transportation Department, will leave Oct. 3, spokeswoman Patricia Klinger said Wednesday.
Quarterman has been at the forefront of the United States’ efforts to improve the safety of trains carrying crude oil amid a string of major explosions in North America since last year.
In July, PHMSA and the Federal Railroad Administration proposed a series of new rules for oil trains to reduce speed, improve braking and phase out the oldest tank cars.
Quarterman has led PHMSA since November 2009.
Reuters first reported the resignation Wednesday.
—This story was updated at 4:36 p.m.