A new report by the International Transport Forum for the Organisation for Economic Co-operation and Development (OECD) examines the relationship between vehicle speed and crash risks.

The study analyzes data from ten countries, identifying the impact of changes in speed limits on crashes and their severity.

“All the cases we studied in ten countries indicated a strong relationship between speed and the number of crashes,” said Véronique Feypell, Manager of the International Transport Forum’s road safety program. “An increase in mean speed was accompanied by a higher number of crashes and casualties. A decrease was associated with fewer crashes and casualties. In no case did an increase in mean speed coincide with fewer crashes or casualties.”

The report references “The Power Model” by Swedish researcher Nilsson, which finds that, as a rule of thumb, a 10 percent increase in mean speed will, on average, lead to a 20 percent increase in all injury crashes, a 30 percent increase in fatal and serious crashes and a 40 percent increase in fatal crashes.

The following recommendations are made in the report:

  • Reduce the speed on roads as well as speed differences between vehicles
  • Set speed limits according to “Safe System” principles
  • Improve infrastructure and enforcement if speed limits are to be increased
  • Use automatic speed control to reduce speed effectively

View the full report.