CMF / CRF Details

CMF ID: 4868

Conversion of intersection to roundabout

Description: Conversion of stop- and signal-controlled intersections into roundabouts

Prior Condition:  Stop- or signal-controlled intersection

Category: Intersection geometry

Study: Evaluating the Performance and Safety Effectiveness of Roundabouts, , 2011

Star Quality Rating:4 Stars  [View score details]
Rating Points Total:130
Crash Modification Factor (CMF)
Adjusted Standard Error:
Unadjusted Standard Error:0.074
Crash Reduction Factor (CRF)
Value:41.7  (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error:7.4
Crash Type:All
Crash Severity:A (serious injury),B (minor injury),C (possible injury)
Roadway Types:All
Street Type:
Minimum Number of Lanes:
Maximum Number of Lanes:
Number of Lanes Direction:
Number of Lanes Comment:
Crash Weather:Not specified
Road Division Type:
Minimum Speed Limit:
Maximum Speed Limit:
Speed Unit:
Speed Limit Comment:
Area Type:All
Traffic Volume:
Average Traffic Volume:
Time of Day:All
If countermeasure is intersection-based
Intersection Type:
Intersection Geometry:Not specified
Traffic Control:Roundabout
Major Road Traffic Volume:Minimum of 1000 to Maximum of 26366 Annual Average Daily Traffic (AADT)
Minor Road Traffic Volume:Minimum of 500 to Maximum of 13750 Annual Average Daily Traffic (AADT)
Average Major Road Volume :11181 Annual Average Daily Traffic (AADT)
Average Minor Road Volume :5600 Annual Average Daily Traffic (AADT)
Development Details
Date Range of Data Used:2001 to 2010
Type of Methodology Used:Before/after using empirical Bayes or full Bayes
Sample Size (crashes):80 crashes after
Other Details
Included in Highway Safety Manual?No
Date Added to Clearinghouse:May 01, 2013
Comments:This CMF includes effects from triple lane roundabouts.