CMF / CRF Details

CMF ID: 10439

Conversion of intersection into high-speed roundabout

Description: Conversion of intersection into high-speed roundabout

Prior Condition: Minor Road Stop-Controlled Intersections

Category: Intersection geometry

Study: Evaluation of Roundabouts on High-Speed Roadways, Bagley, D.L., 2020

 
Star Quality Rating: 3 Stars   [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
Number of Lanes:
Road Division Type:
Speed Limit: 35-55 MPH
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: 2
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.