CMF / CRF Details

CMF ID: 6162

Conversion of signalized intersection into single- or multi-lane roundabout


Prior Condition:  Four-leg signalized intersection with left-turn lane on major route

Category: Intersection geometry

Study: Public Opinion, Traffic Performance, The Environment, and Safety After the Construction of Double-Lane Roundabouts, Hu et al., 2014

Star Quality Rating:2 Stars  [View score details]
Rating Points Total:40
Crash Modification Factor (CMF)
Adjusted Standard Error:
Unadjusted Standard Error:0.501
Crash Reduction Factor (CRF)
Value:34.1  (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error:50.1
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:2
Maximum Number of Lanes:2
Number of Lanes Direction:
Number of Lanes Comment:
Crash Weather:Not specified
Road Division Type:Undivided
Minimum Speed Limit:50
Maximum Speed Limit:50
Speed Unit:mph
Speed Limit Comment:
Area Type:Not specified
Traffic Volume:
Average Traffic Volume:
Time of Day:All
If countermeasure is intersection-based
Intersection Type:Roadway/roadway (not interchange related)
Intersection Geometry:4-leg
Traffic Control:Signalized
Major Road Traffic Volume:
Minor Road Traffic Volume:
Average Major Road Volume :
Average Minor Road Volume :
Development Details
Date Range of Data Used:2003 to 2011
Type of Methodology Used:Regression cross-section
Sample Size (crashes):83 crashes
Sample Size (sites):6 sites
Sample Size (site-years):42 site-years
Other Details
Included in Highway Safety Manual?No
Date Added to Clearinghouse:Mar 11, 2015
Comments:The major road was a two-lane, undivided road prior to construction, but converted to a four-lane, divided road during construction. The total entering volume was approximately 20,300 vehicles per day in the before period and 19,600 vehicles per day in the after period.