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DOT-57 Speed Management Study

Total Cost: $70,481
Project Number:  CTR.4UASFS
Funding Sources: 1997 HURF Bonds 
Completion Date: December 2019 
Managing Dept.: Transportation
Project Map: County-wide

The scope of the study was to investigate the impact of deploying speed feedback signs, supported by varying patterns of speed enforcement, to impact driver speed behavior in a consistent and predictable manner that will be beneficial to road operations and the utilization of enforcement resources. The study explored the relationship between speed feedback signs, posted speed limit enforcement, and speed of travel as a system so that Pima County Department of Transportation (PCDOT) can achieve better operations (in terms of number of crashes, reduced severity, and better utilization of capacity). These findings will support PCDOT in developing strategies to use both in implementing cost effective safety interventions and improving signal timing plans.

This study examined the impact of three different speed management strategies, namely: 1) Speed Feedback Sign (SFS), 2) Periodic law enforcement (E), and 3) SFS supported by periodic law enforcement in reducing trucks’ and passenger cars’ speeds.  In order to evaluate the impact of each enforcement strategy, a cross-sectional study design was set up in Pima County, Arizona. In total, nine study sites were selected: three sites with SFS, three sites with periodic law enforcement, and three sites with SFS supported with periodic law enforcement.

The general effect of the speed management strategies (SFS, E, and SFS+E) showed that all the strategies were effective in reducing average speed and percent of drivers exceeding the speed limit. The results of comparing the effectiveness of speed management strategies showed that the speed feedback sign supported with periodic law enforcement is the most effective strategy.

speed feedback sign