CMF / CRF Details

CMF ID: 2841

Converting four-lane roadways to three-lane roadways with center turn lane (road diet)

Description: Conversion of road segments from a four-lane to a three-lane cross-section with two-way left-turn lanes (also known as road diets).

Prior Condition: Four-lane undivided roadway

Category: Roadway

Study: Comparison of empirical Bayes and full Bayes approaches for before–after road safety evaluations, Persaud et. al, 2010

 
Star Quality Rating: 4 Stars   [View score details]
Crash Modification Factor (CMF)
Value: 0.47
Adjusted Standard Error:
Unadjusted Standard Error: 0.01
Crash Reduction Factor (CRF)
Value: 53 (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error: 1
Applicability
Crash Type: All
Crash Severity: All
Roadway Types: Not Specified
Number of Lanes: 4
Road Division Type: Undivided
Speed Limit:
Area Type: Suburban
Traffic Volume:
Time of Day: All
If countermeasure is intersection-based
Intersection Type:
Intersection Geometry:
Traffic Control:
Major Road Traffic Volume:
Minor Road Traffic Volume:
Development Details
Date Range of Data Used: 1982 to 2004
Municipality:
State:
Country:
Type of Methodology Used: Before/after using empirical Bayes or full Bayes
Sample Size Used: Site-years
Before Sample Size Used: 263 Site-years
After Sample Size Used: 67 Site-years
Other Details
Included in Highway Safety Manual? No
Date Added to Clearinghouse: 03-21-2011
Comments:

[View the Full Study Details]

 

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