CMF / CRF Details

CMF ID: 9445

Convert to roundabout interchanges

Description: Convert to interchange roundabouts with either a single roundabout or a pair.

Prior Condition: Interchanges without roundabout ramp terminals

Category: Interchange design

Study: Safety Performance Analysis of Roundabout Interchanges in Missouri, , 2018

 
Star Quality Rating: 3 Stars   [View score details]
Crash Modification Factor (CMF)
Value: 0.756
Adjusted Standard Error:
Unadjusted Standard Error:
Crash Reduction Factor (CRF)
Value: 24.4   (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error:
Applicability
Crash Type: All
Crash Severity: All
Roadway Types: All
Number of Lanes: 1
Road Division Type:
Speed Limit: 25-45
Area Type: All
Traffic Volume:
Average Traffic Volume:
Time of Day: All
If countermeasure is intersection-based
Intersection Type: Roadway/roadway (interchange ramp terminal)
Intersection Geometry: No values chosen.
Traffic Control: Roundabout
Major Road Traffic Volume: Minimum of 2060 to Maximum of 16715 Annual Average Daily Traffic (AADT)
Minor Road Traffic Volume: Minimum of 647 to Maximum of 5630 Annual Average Daily Traffic (AADT)
Average Major Road Volume : 8186 Annual Average Daily Traffic (AADT)
Average Minor Road Volume : 2721 Annual Average Daily Traffic (AADT)
Development Details
Date Range of Data Used: 2003 to 2016
Municipality:
State: MO
Country:
Type of Methodology Used: Before/after using empirical Bayes or full Bayes
Sample Size (crashes): 80 crashes after
Sample Size (sites): 7 sites before, 7 sites after
Sample Size (site-years): 27.5 site-years before, 33.5 site-years after
Other Details
Included in Highway Safety Manual? No
Date Added to Clearinghouse: Oct-27-2018
Comments: This CMF is for all crashes at single-lane roundabout ramp terminals. Number of lanes and speed limits entered here are for ramps.