CMF / CRF Details

CMF ID: 10443

Conversion of intersection into high-speed roundabout


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

Crash Modification Factor (CMF)
Value:	0.45
Adjusted Standard Error:
Unadjusted Standard Error:	0.13

Crash Reduction Factor (CRF)
Value:	55 (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error:	13

Applicability
Crash Type:	Other
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:	This CMF is for Frontal Impact Crashes. 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.