title: Traffic speeds associated with implementation of 80 mph speed limits on West Texas rural interstates.
abstract: OBJECTIVE
  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.
  
  
  CONCLUSIONS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Insurance Institute for Highway Safety, Arlington, VA 22201 USA. rretting@iihs.org
authors.forename: Richard
authors.initials: R
authors.lastname: Retting
authors.forename: Ivan
authors.initials: I
authors.lastname: Cheung
mesh_terms: D000063:Accidents, Traffic / Q000331:legislation & jurisprudence / Q000706:statistics & numerical data*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D002648:Child; D002675:Child, Preschool; D016001:Confidence Intervals; D005260:Female; D033161:Government Regulation; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D018986:Motor Vehicles / Q000331:legislation & jurisprudence / Q000706:statistics & numerical data*; D011634:Public Health / Q000706:statistics & numerical data; D011640:Public Policy; D018570:Risk Assessment; D012307:Risk Factors; D012424:Rural Population / Q000706:statistics & numerical data*; D013781:Texas; D055815:Young Adult