CMF / CRF Details

CMF ID: 10432

Conversion of intersection to roundabout

Description: Conversion of stop- and signal-controlled intersections into roundabouts

Prior Condition: No Prior Condition(s)

Category: Intersection geometry

Study: Effect of traffic roundabouts on accident rate and severity in Arizona, Mamlouk and Souliman, 2019

 
Star Quality Rating: 2 Stars   [View score details]
Rating Points Total: 35
Crash Modification Factor (CMF)
Value: 0.89
Adjusted Standard Error:
Unadjusted Standard Error:
Crash Reduction Factor (CRF)
Value: 11   (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error:
Applicability
Crash Type: All
Crash Severity: B (minor injury),C (possible injury)
Roadway Types: Not specified
Number of Lanes:
Road Division Type:
Speed Limit:
Area Type: Urban
Traffic Volume:
Average Traffic Volume:
Time of Day: Not specified
If countermeasure is intersection-based
Intersection Type: Roadway/roadway (not interchange related)
Intersection Geometry: Not specified
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:
Municipality:
State: AZ
Country: USA
Type of Methodology Used: 3
Sample Size (sites): 6 sites before, 6 sites after
Other Details
Included in Highway Safety Manual? No
Date Added to Clearinghouse: Jun-01-2020
Comments: For double-lane roundabout. Change in accident rate per year. 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.