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)
Value: 0.659
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
Number of Lanes: 2
Road Division Type: Undivided
Speed Limit: 50
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
Municipality: Bellingham
State: WA
Type of Methodology Used: 7
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.