Cynthia Quarterman will resign her post as administrator of the U.S. Department of Transportation’s Pipeline and Hazardous Materials Safety Administration (PHMSA) effective Oct. 3, officials told The Wall Street Journal (WSJ).

PHMSA has been under the public microscope of late due to a string of rail accidents involving the transportation of crude oil, which has led to a call for new regulations to match the increased use of rail as a transportation system for crude.

The agency proposed new regulations in July that would phase out older tank cars used to transport crude and has been in the process of drafting final rules. The deadline for public comment on these proposals is Sept. 30.

Despite these efforts, critics—including a report issued this week from the U.S. Government Accountability Office—have stated that the agency hasn’t moved fast enough to meet public safety needs.

PHMSA officials declined to comment on the resignation other than providing the WSJ with a copy of Quarterman’s email to PHMSA staff informing them of her resignation.

“We have both closed regulatory gaps and removed unnecessary regulatory hurdles … We have held regulated industries accountable through strengthened oversight and enforcement, but also improved outreach and training to them, the public and the response community,” she said in the email.

Quarterman served in the post, which required Congressional approval, since 2009.