CMF / CRF Details

CMF ID: 4867

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: 5 Stars   [View score details]
Rating Points Total: 135
Crash Modification Factor (CMF)
Value: 1.346
Adjusted Standard Error:
Unadjusted Standard Error: 0.059
Crash Reduction Factor (CRF)
Value: -34.6   (This value indicates an increase in crashes)
Adjusted Standard Error:
Unadjusted Standard Error: 5.9
Crash Type: All
Crash Severity: All
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
State: MI
Type of Methodology Used: Before/after using empirical Bayes or full Bayes
Sample Size (crashes): 962 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.