Citation

Retting R, Cheung I. J. Saf. Res. 2008; 39(5): 529-534.

Affiliation

Insurance Institute for Highway Safety 1005 North Glebe Road, Arlington, VA 22201 USA.

Copyright

(Copyright © 2008, U.S. National Safety Council, Publisher Elsevier Publishing)

DOI

10.1016/j.jsr.2008.08.005

PMID

19010126

Abstract

PROBLEM: In 2006 Texas raised the daytime speed limit for passenger vehicles on segments of I-10 and I-20 from 75 to 80 mph. Methods: Traffic speeds were measured before and 3, 12, and 16 months after the limit was changed. Results: During the 16-month period following the speed limit increase, mean speeds of passenger vehicles on I-20 increased by 9 mph relative to the comparison road, where no speed limit change occurred and traffic speeds declined. On I-10 mean speeds increased by 4 mph relative to the comparison road. Limiting the analysis to the month before the speed limit change and 1 year later, the proportion of drivers exceeding 80 mph was 18 times higher on I-20 and 2 times higher on I-10. Discussion: The smaller speed increases on I-10 may be related to its proximity to the U.S. border with Mexico. Highly visible border patrol activity coincided with posting of the higher speed limit. Long-term monitoring in other states suggests that traffic speeds in Texas are likely to continue to increase. Impact on Industry: The present study adds to the wealth of evidence that increased speed limits lead to increased travel speeds. The primary countermeasures to reduce the risk of speed-related crashes include highly visible police traffic enforcement and the use of speed cameras accompanied by publicity.

Language: en