WASHINGTON, D.C. — After three years at the helm of the National Highway Traffic Safety Administration (NHTSA), David Strickland is stepping down as administrator.

Under Strickland’s watch, NHTSA has shown support for safety-related issues in transportation, such as drunken driving prevention, and it has worked to promote school bus transportation.

In 2011, Strickland was among the high-profile speakers at the National Association of State Directors of Pupil Transportation Services’ (NASDPTS) conference in Cincinnati. He touted the safety and environmental benefits of yellow buses, and he told conferees, “We need to think about how we can expand busing — how we get more kids on buses.”

During that conference, NHTSA presented new materials that promoted school bus transportation, which included posters that, among other messages, describe the safety features of yellow buses.

Following the 2011 NASDPTS conference, Strickland spoke to SBF Executive Editor Thomas McMahon in an exclusive interview about topics ranging from seat belts on school buses to his personal experiences with the vehicles.

Strickland supported drunken driving prevention as well, having served as honorary chairman of Mothers Against Drunk Driving (MADD)’s Campaign to Eliminate Drunk Driving.

The organization reports that he had recently announced the Seamless and Significant Initiative, which calls for new vehicle-based technologies to save lives. Included in this initiative is the Driver Alcohol Detection System for Safety program, which seeks to develop in-vehicle technology that could passively and unobtrusively determine if a driver’s blood alcohol concentration level is at or above .08 — the illegal level in all 50 states.

“We will certainly miss David and wish him our best in his future endeavors,” said Jan Withers, national president of MADD. “He is a longtime friend to MADD, and we appreciate his great service to our mutual cause.”

The reason for Strickland’s departure is not known. Nathan Naylor, a spokesman for NHTSA, told the Detroit Free Press that Deputy Administrator David Friedman will serve as acting administrator after Strickland leaves. Friedman, formerly a senior engineer with the Union of Concerned Scientists, became deputy in May.