CMF / CRF Details

CMF ID: 4706

Convert high-speed rural intersection to roundabout

Description: Convert high-speed rural intersection to roundabout

Prior Condition:  Stop controlled intersection (3 or 4 leg)

Category: Intersection geometry

Study: A Statistical Analysis and Development of a Crash Prediction Model for Roundabouts on High-Speed Rural Roadways, Isebrands, 2012

 
Star Quality Rating:2 Stars  [View score details]
Rating Points Total:70
Crash Modification Factor (CMF)
Value:0.85
Adjusted Standard Error:
Unadjusted Standard Error:
Crash Reduction Factor (CRF)
Value:15  (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error:
Applicability
Crash Type:Rear end
Crash Severity:All
Roadway Types:Not specified
Street Type:
Minimum Number of Lanes:1
Maximum Number of Lanes:2
Number of Lanes Direction:
Number of Lanes Comment:
Crash Weather:Not specified
Road Division Type:
Minimum Speed Limit:40
Maximum Speed Limit:65
Speed Unit:mph
Speed Limit Comment:
Area Type:Rural
Traffic Volume:
Average Traffic Volume:
Time of Day:
If countermeasure is intersection-based
Intersection Type:Roadway/roadway (not interchange related)
Intersection Geometry:3-leg,4-leg
Traffic Control:Roundabout
Major Road Traffic Volume:
Minor Road Traffic Volume:
Average Major Road Volume :14000 Annual Average Daily Traffic (AADT)
Average Minor Road Volume :5600 Annual Average Daily Traffic (AADT)
Development Details
Date Range of Data Used:
Municipality:
State:KS,MD,MN,OR,WA,WI
Country:
Type of Methodology Used:Simple before/after
Sample Size (site-years):98 site-years before, 98 site-years after
Other Details
Included in Highway Safety Manual?No
Date Added to Clearinghouse:May 01, 2013
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.