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, Claros et al., 2018

 
Star Quality Rating:3 Stars  [View score details]
Rating Points Total:90
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
Street Type:
Minimum Number of Lanes:1
Maximum Number of Lanes:1
Number of Lanes Direction:
Number of Lanes Comment:
Crash Weather:Not specified
Road Division Type:
Minimum Speed Limit:25
Maximum Speed Limit:45
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 (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.