CMF / CRF Details

CMF ID: 6163

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: 1.132
Adjusted Standard Error:
Unadjusted Standard Error: 0.479
Crash Reduction Factor (CRF)
Value: -13.2   (This value indicates an increase in crashes)
Adjusted Standard Error:
Unadjusted Standard Error: 47.9
Crash Type: All
Crash Severity: O (property damage only)
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
Municipality: Bellingham
State: WA
Type of Methodology Used: Regression cross-section
Sample Size (crashes): 129 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.