CMF / CRF Details

CMF ID: 10582

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)
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
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 diameter of the central island (m)