Road safety

Cover of Evaluation of Speed Limiting Locally Operating Warning Signs
Evaluation of Speed Limiting Locally Operating Warning Signs
  • Publication no: AP-R278-05
  • ISBN: 1 921139 09 9
  • Published: 1 November 2005
This study investigated the efficacy of Speed Limiting Locally Operating Warning Signs (SLLOWS) at a number of sites in the Perth metropolitan area. It was found that SLLOWS were successful in reducing vehicle speed at all locations (3-4 km/h on average), although the magnitude of the effect varied across locations. While there was generally a residual (halo) effect after the signs were removed, the magnitude of this effect was small (of the order of 1 km/h). It was also found that the effectiveness of SLLOWS was quite local; speeds reverted to pre-SLLOWS levels by 460 metres downstream of the sign. Finally, there was evidence that deployment of SLLOWS across successive days of the week resulted in a gradual decrease in efficacy (habituation effect). It was concluded that SLLOWS are most useful when they are employed as temporary and local speed moderating tools.
  • AP-R278/05 Evaluation of Speed Limiting Locally Operating Warning Signs
  • EXECUTIVE SUMMARY
  • CONTENTS
  • TABLES
  • FIGURES
  • 1. INTRODUCTION
    • 1.1. Driver Awareness
    • 1.2. Impact upon Excessive Speeds
    • 1.3. The Halo Effect
    • 1.4. Cost Effectiveness
    • 1.5. Confounding Factors
  • 2. VMS IMPLEMENTATION IN WESTERN AUSTRALIA
  • 3. SLLOWS TRIAL
    • 3.1. Methodology
      • 3.1.1. SLLOWS Effectiveness Over Time
      • 3.1.2. SLLOWS Effectiveness Over Distance
      • 3.1.3. SLLOWS Effectiveness Over Successive Deployment
      • 3.1.4. Measure of Effectiveness
  • 4. RESULTS
    • 4.1. SLLOWS Effectiveness Over Time
      • 4.1.1. Average Speed
      • 4.1.2. 85th Percentile Speed
      • 4.1.3. Percent Exceeding the Speed Limit
      • 4.1.4. Percent Exceeding the Speed Limit by 10 km/h or More
      • 4.1.5. Percent Exceeding the Speed Limit by 20 km/h or More
      • 4.1.6. Percent Exceeding the Speed Limit by 30 km/h or More
    • 4.2. SLLOWS Effectiveness Over Distance
      • 4.2.1. Mean Speed
      • 4.2.2. 85th Percentile Speeds
      • 4.2.3. Percent Exceeding the Speed Limit
      • 4.2.4. Measure of Effectiveness
      • 4.2.5. SLLOWS Effectiveness Over Successive Deployments
    • 4.3. SLLOWS Effectiveness over the Different Sites
  • 5. DISCUSSION
    • 5.1. Recommended Applications for SLLOWS
      • 5.1.1. Speed Reduction
      • 5.1.2. Community Education
  • REFERENCES
  • INFORMATION RETRIEVAL