CMF / CRF Details

CMF ID: 10439

Conversion of intersection into high-speed roundabout


Star Quality Rating:	[View score details]
Rating Points Total:	105

Crash Modification Factor (CMF)
Value:	0.57
Adjusted Standard Error:
Unadjusted Standard Error:	0.11

Crash Reduction Factor (CRF)
Value:	43 (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error:	11

Applicability
Crash Type:	All
Crash Severity:	All
Roadway Types:	All
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:	35
Maximum Speed Limit:	55
Speed Unit:	mph
Speed Limit Comment:
Area Type:	All
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:	Roundabout
Major Road Traffic Volume:
Minor Road Traffic Volume:
Average Major Road Volume :
Average Minor Road Volume :

Development Details
Date Range of Data Used:	1999 to 2019
Municipality:
State:	NC
Country:
Type of Methodology Used:	Before/after using empirical Bayes or full Bayes
Sample Size (sites):	9 sites before, 9 sites after
Sample Size (site-years):	27 site-years before, 27 site-years after

Other Details
Included in Highway Safety Manual?	No
Date Added to Clearinghouse:	Jun 01, 2020
Comments:	The number of crashes in the after period were not reported in this study, however, they have been recorded as 300 to give 10 points as a beneift of doubt for one or more of the following: (1) number of miles/sites in the reference/treatment group, (2) number of crashes in the references/treatment group, (3) reporting AADTs for the aggregate dataset but not for the disaggragate dataset used for CMF development.