Whether conversion and weather matter to roundabout safety

Area of Science:

• Traffic Engineering
• Road Safety Analysis
• Transportation Planning

Background:

• Roundabouts are increasingly implemented for intersection traffic control, aiming to enhance safety and efficiency.
• Limited data exists on roundabout performance, particularly concerning safety during inclement weather conditions.

Purpose of the Study:

• To assess the safety impact of converting signal-controlled intersections to modern roundabouts.
• To investigate the influence of rainfall on roundabout safety compared to signalized intersections.

Main Methods:

• Empirical Bayes approach to analyze safety effects of intersection conversion.
• Matched-pair comparison to evaluate collision risk under inclement weather.

Main Results:

• Conversion to roundabouts reduced injury/fatal collisions by 20% but increased property-damage collisions.
• Roundabouts showed no significant increase in crashes during rainfall, unlike signalized intersections which saw a 4%-22% risk increase.

Conclusions:

• Roundabouts are effective in reducing severe collisions, though drivers may need time to adapt to property-damage incident increases.
• Roundabouts demonstrate superior safety performance in rainy conditions compared to signalized intersections.