Demonstration and Evaluation of Rational Speed Limits PDF Download

Author: Michael D. Fontaine
Publisher:
ISBN:
Category : Automobile drivers
Languages : en
Pages : 87

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Book Description
This report presents the results of a field implementation of credible, well-enforced, and highly publicized speed limits on two limited access highways in Virginia. The two locations studied were the US 29 bypass around Altavista, VA and the US 58/US 220 bypass around Martinsville, VA. At both of these locations, an engineering study recommended that the posted speed limit be increased from 55 mph to 65 mph. Virginia State Police provided an additional 40 hours per month of overtime enforcement on the study sections for 1 year at the Martinsville site and 15 months at the Altavista site. A public information and education (PI & E) campaign that consisted of media reports, informational handouts, and educational roadside signs was also implemented to try to increase compliance with the new posted speed limits. Before and after data on public perception, crash experience, and speed were analyzed to assess the impact of the program. The public perception survey results showed that the new 65 mph speed limits were well supported by the public, with over 80 percent agreeing with the new speed limits. The speed data analysis showed that the average speed increased by a statistically significant margin of 3 to 4 mph immediately after the new speed limit was implemented. Speeds remained constant following the implementation of the new speed limit, even after the increased enforcement and the education campaign ended. A speed analysis by vehicle type showed some minor variations in how vehicles responded to the changes in speed limit, enforcement, and PI & E. These differences were usually not very large, however. No negative safety impacts were observed during the evaluation. The overall number of crashes did not change by a statistically significant margin relative to historic trends, although the number of severe crashes at the Martinsville site did decline by a statistically significant amount and the crash rate at Altavista showed more than a 20 percent decline. Speed variance did not significantly change between the period with the 55 mph limit and the period with the 65 mph limit. This suggests that crash likelihood was not increased due to the increased posted speed limit. The coefficient of variation of the speeds decreased slightly following the increase in speed limit, potentially indicating that interactions between vehicles may have declined slightly. The demonstration proved to be a success, with the change in speed limit being well supported by the public. Strict compliance with the posted speed limits improved from 5 to 10 percent before the project began to between 45 and 50 percent. The percentage of drivers traveling 10 mph or more over the limit declined from over 20 percent to only 2 to 3 percent. Survey respondents reported that the roadside signs were noticed the most often of any PI & E effort used, likely due to the fact that both sites were located on through routes in rural areas.