CMF / CRF Details

CMF ID: 4225

Convert signalized intersection to modern roundabout

Description:

Prior Condition: Four-leg signalized intersection at interchange ramp terminal converted to a four-leg, one-lane, non-circular “eye drop” roundabout

Category: Intersection geometry

Study: Performance Evaluation of Roundabouts for Traffic Flow Improvements and Crash Reductions at a Highway Interchange in Oxford, MS, Uddin, Headrick, and Sullivan, 2012

 
Star Quality Rating: 2 Stars   [View score details]
Rating Points Total: 35
Crash Modification Factor (CMF)
Value: 0.4
Adjusted Standard Error:
Unadjusted Standard Error:
Crash Reduction Factor (CRF)
Value: 60   (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error:
Applicability
Crash Type: All
Crash Severity: A (serious injury),B (minor injury),C (possible injury)
Roadway Types: Principal Arterial Other
Number of Lanes: 1
Road Division Type: Undivided
Speed Limit:
Area Type: Rural
Traffic Volume:
Average Traffic Volume:
Time of Day: Not specified
If countermeasure is intersection-based
Intersection Type: Roadway/roadway (interchange ramp terminal)
Intersection Geometry: 4-leg
Traffic Control: Signalized
Major Road Traffic Volume:
Minor Road Traffic Volume:
Average Major Road Volume :
Average Minor Road Volume :
Development Details
Date Range of Data Used: 2005 to 2009
Municipality: Oxford
State: MS
Country: United States
Type of Methodology Used: 2
Sample Size (site-years): 2.5 site-years before, 2.5 site-years after
Other Details
Included in Highway Safety Manual? No
Date Added to Clearinghouse: Nov-01-2012
Comments: Countermeasure name has been slightly modified for consistency across Clearinghouse 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.