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Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations

This report is an archived publication and may contain dated technical, contact, and link information
Publication Number: FHWA-HRT-05-042
Date: October 2005

Safety Effects of Differential Speed Limits

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The investigators gratefully acknowledge the many persons who provided data, insights, assistance, and other contributions to this effort. Any person who has worked with State crash and speed data will recognize that obtaining these data, especially data from as far back as a dozen years ago, is no small undertaking. Thus, assistance from K. Bonds (AR), J. Williams (AZ), C. Haack and J. Benton (CA), N. Brizzi (ID), L. Rust (IN), W. Baldwin, G. Groat, M. Pawlovich, and T. Welch (IA), J. Schaefer (MO), P. Jomini and V. Gonzales (MT), S. Cosper and A. Wyatt (NC), L. Evans, D. Gardner, J. Hausman, and S. Shokouhi (OH), S. Reed (OR), R. Collins and M. Moore (TX), B. Siddiqui (UT), T. Rickman and K. Tanner (WA), J. Legg, R. Lewis, and R. Russell (WV) proved essential to this study. Insights from D. Lord and E. Hauer also proved essential for application of the empirical Bayes method. Finally, the team also could not have accomplished this work without the assistance of L. Woodson (VA), whose expertise in data reduction was needed. Inclusion of the above names and States does not imply, however, agreement with the results of this study.


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