CMF / CRF Details

CMF ID: 10571

Roundabout geometry

Description: Various geometric elements of roundabout

Prior Condition: No Prior Condition(s)

Category: Intersection geometry

Study: Developing crash modification factors for roundabouts using a cross-sectional method, Al-Marafi et al., 2020

Star Quality Rating: 2 Stars   [View score details]
Rating Points Total: 70
Crash Modification Factor (CMF)
Value: Equation
Adjusted Standard Error:
Unadjusted Standard Error:
Crash Reduction Factor (CRF)
Adjusted Standard Error:
Unadjusted Standard Error:
Crash Type: All
Crash Severity: K (fatal),A (serious injury),B (minor injury),C (possible injury)
Roadway Types: Not specified
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: Not specified
Traffic Volume:
Average Traffic Volume:
Time of Day:
If countermeasure is intersection-based
Intersection Type: Roadway/roadway (not interchange related)
Intersection Geometry: No values chosen.
Traffic Control: Roundabout
Major Road Traffic Volume: Minimum of 1288 to Maximum of 16071 Annual Average Daily Traffic (AADT)
Minor Road Traffic Volume: Minimum of 1200 to Maximum of 10002 Annual Average Daily Traffic (AADT)
Average Major Road Volume : 6966 Annual Average Daily Traffic (AADT)
Average Minor Road Volume : 4341 Annual Average Daily Traffic (AADT)
Development Details
Date Range of Data Used: 2010 to 2015
Municipality: Toowoomba City
Country: Australia
Type of Methodology Used: Regression cross-section
Sample Size (sites): 49 sites
Other Details
Included in Highway Safety Manual? No
Date Added to Clearinghouse: Dec-17-2020
Comments: CMFunction for entry width on the minor approach (m)