Acknowledgments

U.S. Department of Transportation

Ray LaHood
Secretary

John D. Porcari
Deputy Secretary

Research and Innovative Technology Administration

Peter H. Appel
Administrator

Robert L. Bertini, Ph.D.
Deputy Administrator

Bureau of Transportation Statistics

Steven D. Dillingham, Ph.D.
Director

Steven K. Smith, Ph.D.
Deputy Director

Produced under the Direction of:

Deborah Johnson
Assistant Director for Transportation Analysis

Project Manager

Sean Jahanmir

Contributors

David Chesser, Ph.D.
Vincent Fang, Ph.D.
Chester Ford
Xiaoli Han, Ph.D.
Getachew Mekonnen
Adam Mengesha
William Moore
Long Nguyen
Hilary Ross
Alpha Glass Wingfield
Jie Zhang